diff --git a/api/current.txt b/api/current.txt
index 746d31a..0e083c2 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -35923,24 +35923,25 @@
     enum_constant public static final android.webkit.ConsoleMessage.MessageLevel WARNING;
   }
 
-  public class CookieManager {
-    method public synchronized boolean acceptCookie();
-    method public boolean acceptThirdPartyCookies(android.webkit.WebView);
+  public abstract class CookieManager {
+    ctor public CookieManager();
+    method public abstract boolean acceptCookie();
+    method public abstract boolean acceptThirdPartyCookies(android.webkit.WebView);
     method public static boolean allowFileSchemeCookies();
-    method public void flush();
-    method public java.lang.String getCookie(java.lang.String);
+    method public abstract void flush();
+    method public abstract java.lang.String getCookie(java.lang.String);
     method public static synchronized android.webkit.CookieManager getInstance();
-    method public synchronized boolean hasCookies();
-    method public deprecated void removeAllCookie();
-    method public void removeAllCookies(android.webkit.ValueCallback<java.lang.Boolean>);
-    method public deprecated void removeExpiredCookie();
-    method public deprecated void removeSessionCookie();
-    method public void removeSessionCookies(android.webkit.ValueCallback<java.lang.Boolean>);
-    method public synchronized void setAcceptCookie(boolean);
+    method public abstract boolean hasCookies();
+    method public abstract deprecated void removeAllCookie();
+    method public abstract void removeAllCookies(android.webkit.ValueCallback<java.lang.Boolean>);
+    method public abstract deprecated void removeExpiredCookie();
+    method public abstract deprecated void removeSessionCookie();
+    method public abstract void removeSessionCookies(android.webkit.ValueCallback<java.lang.Boolean>);
+    method public abstract void setAcceptCookie(boolean);
     method public static void setAcceptFileSchemeCookies(boolean);
-    method public void setAcceptThirdPartyCookies(android.webkit.WebView, boolean);
-    method public void setCookie(java.lang.String, java.lang.String);
-    method public void setCookie(java.lang.String, java.lang.String, android.webkit.ValueCallback<java.lang.Boolean>);
+    method public abstract void setAcceptThirdPartyCookies(android.webkit.WebView, boolean);
+    method public abstract void setCookie(java.lang.String, java.lang.String);
+    method public abstract void setCookie(java.lang.String, java.lang.String, android.webkit.ValueCallback<java.lang.Boolean>);
   }
 
   public final deprecated class CookieSyncManager extends android.webkit.WebSyncManager {
@@ -36049,11 +36050,13 @@
     method public abstract void onReceiveValue(T);
   }
 
-  public class WebBackForwardList implements java.lang.Cloneable java.io.Serializable {
-    method public synchronized int getCurrentIndex();
-    method public synchronized android.webkit.WebHistoryItem getCurrentItem();
-    method public synchronized android.webkit.WebHistoryItem getItemAtIndex(int);
-    method public synchronized int getSize();
+  public abstract class WebBackForwardList implements java.lang.Cloneable java.io.Serializable {
+    ctor public WebBackForwardList();
+    method protected abstract android.webkit.WebBackForwardList clone();
+    method public abstract int getCurrentIndex();
+    method public abstract android.webkit.WebHistoryItem getCurrentItem();
+    method public abstract android.webkit.WebHistoryItem getItemAtIndex(int);
+    method public abstract int getSize();
   }
 
   public class WebChromeClient {
@@ -36105,21 +36108,24 @@
     field public static final int MODE_SAVE = 3; // 0x3
   }
 
-  public class WebHistoryItem implements java.lang.Cloneable {
-    method public android.graphics.Bitmap getFavicon();
-    method public java.lang.String getOriginalUrl();
-    method public java.lang.String getTitle();
-    method public java.lang.String getUrl();
+  public abstract class WebHistoryItem implements java.lang.Cloneable {
+    ctor public WebHistoryItem();
+    method protected abstract android.webkit.WebHistoryItem clone();
+    method public abstract android.graphics.Bitmap getFavicon();
+    method public abstract java.lang.String getOriginalUrl();
+    method public abstract java.lang.String getTitle();
+    method public abstract java.lang.String getUrl();
   }
 
-  public deprecated class WebIconDatabase {
-    method public void close();
+  public abstract deprecated class WebIconDatabase {
+    ctor public WebIconDatabase();
+    method public abstract void close();
     method public static android.webkit.WebIconDatabase getInstance();
-    method public void open(java.lang.String);
-    method public void releaseIconForPageUrl(java.lang.String);
-    method public void removeAllIcons();
-    method public void requestIconForPageUrl(java.lang.String, android.webkit.WebIconDatabase.IconListener);
-    method public void retainIconForPageUrl(java.lang.String);
+    method public abstract void open(java.lang.String);
+    method public abstract void releaseIconForPageUrl(java.lang.String);
+    method public abstract void removeAllIcons();
+    method public abstract void requestIconForPageUrl(java.lang.String, android.webkit.WebIconDatabase.IconListener);
+    method public abstract void retainIconForPageUrl(java.lang.String);
   }
 
   public static abstract deprecated interface WebIconDatabase.IconListener {
@@ -36151,98 +36157,99 @@
   }
 
   public abstract class WebSettings {
-    method public deprecated boolean enableSmoothTransition();
-    method public boolean getAllowContentAccess();
-    method public boolean getAllowFileAccess();
+    ctor public WebSettings();
+    method public abstract deprecated boolean enableSmoothTransition();
+    method public abstract boolean getAllowContentAccess();
+    method public abstract boolean getAllowFileAccess();
     method public abstract boolean getAllowFileAccessFromFileURLs();
     method public abstract boolean getAllowUniversalAccessFromFileURLs();
-    method public synchronized boolean getBlockNetworkImage();
-    method public synchronized boolean getBlockNetworkLoads();
-    method public boolean getBuiltInZoomControls();
-    method public int getCacheMode();
-    method public synchronized java.lang.String getCursiveFontFamily();
-    method public synchronized boolean getDatabaseEnabled();
-    method public deprecated synchronized java.lang.String getDatabasePath();
-    method public synchronized int getDefaultFixedFontSize();
-    method public synchronized int getDefaultFontSize();
-    method public synchronized java.lang.String getDefaultTextEncodingName();
+    method public abstract boolean getBlockNetworkImage();
+    method public abstract boolean getBlockNetworkLoads();
+    method public abstract boolean getBuiltInZoomControls();
+    method public abstract int getCacheMode();
+    method public abstract java.lang.String getCursiveFontFamily();
+    method public abstract boolean getDatabaseEnabled();
+    method public abstract deprecated java.lang.String getDatabasePath();
+    method public abstract int getDefaultFixedFontSize();
+    method public abstract int getDefaultFontSize();
+    method public abstract java.lang.String getDefaultTextEncodingName();
     method public static java.lang.String getDefaultUserAgent(android.content.Context);
-    method public deprecated android.webkit.WebSettings.ZoomDensity getDefaultZoom();
-    method public boolean getDisplayZoomControls();
-    method public synchronized boolean getDomStorageEnabled();
-    method public synchronized java.lang.String getFantasyFontFamily();
-    method public synchronized java.lang.String getFixedFontFamily();
-    method public synchronized boolean getJavaScriptCanOpenWindowsAutomatically();
-    method public synchronized boolean getJavaScriptEnabled();
-    method public synchronized android.webkit.WebSettings.LayoutAlgorithm getLayoutAlgorithm();
-    method public deprecated boolean getLightTouchEnabled();
-    method public boolean getLoadWithOverviewMode();
-    method public synchronized boolean getLoadsImagesAutomatically();
-    method public boolean getMediaPlaybackRequiresUserGesture();
-    method public synchronized int getMinimumFontSize();
-    method public synchronized int getMinimumLogicalFontSize();
+    method public abstract deprecated android.webkit.WebSettings.ZoomDensity getDefaultZoom();
+    method public abstract boolean getDisplayZoomControls();
+    method public abstract boolean getDomStorageEnabled();
+    method public abstract java.lang.String getFantasyFontFamily();
+    method public abstract java.lang.String getFixedFontFamily();
+    method public abstract boolean getJavaScriptCanOpenWindowsAutomatically();
+    method public abstract boolean getJavaScriptEnabled();
+    method public abstract android.webkit.WebSettings.LayoutAlgorithm getLayoutAlgorithm();
+    method public abstract deprecated boolean getLightTouchEnabled();
+    method public abstract boolean getLoadWithOverviewMode();
+    method public abstract boolean getLoadsImagesAutomatically();
+    method public abstract boolean getMediaPlaybackRequiresUserGesture();
+    method public abstract int getMinimumFontSize();
+    method public abstract int getMinimumLogicalFontSize();
     method public abstract int getMixedContentMode();
-    method public deprecated synchronized android.webkit.WebSettings.PluginState getPluginState();
-    method public synchronized java.lang.String getSansSerifFontFamily();
-    method public boolean getSaveFormData();
-    method public deprecated boolean getSavePassword();
-    method public synchronized java.lang.String getSerifFontFamily();
-    method public synchronized java.lang.String getStandardFontFamily();
+    method public abstract deprecated android.webkit.WebSettings.PluginState getPluginState();
+    method public abstract java.lang.String getSansSerifFontFamily();
+    method public abstract boolean getSaveFormData();
+    method public abstract deprecated boolean getSavePassword();
+    method public abstract java.lang.String getSerifFontFamily();
+    method public abstract java.lang.String getStandardFontFamily();
     method public deprecated synchronized android.webkit.WebSettings.TextSize getTextSize();
-    method public synchronized int getTextZoom();
-    method public synchronized boolean getUseWideViewPort();
-    method public synchronized java.lang.String getUserAgentString();
-    method public void setAllowContentAccess(boolean);
-    method public void setAllowFileAccess(boolean);
+    method public abstract int getTextZoom();
+    method public abstract boolean getUseWideViewPort();
+    method public abstract java.lang.String getUserAgentString();
+    method public abstract void setAllowContentAccess(boolean);
+    method public abstract void setAllowFileAccess(boolean);
     method public abstract void setAllowFileAccessFromFileURLs(boolean);
     method public abstract void setAllowUniversalAccessFromFileURLs(boolean);
-    method public synchronized void setAppCacheEnabled(boolean);
-    method public deprecated synchronized void setAppCacheMaxSize(long);
-    method public synchronized void setAppCachePath(java.lang.String);
-    method public synchronized void setBlockNetworkImage(boolean);
-    method public synchronized void setBlockNetworkLoads(boolean);
-    method public void setBuiltInZoomControls(boolean);
-    method public void setCacheMode(int);
-    method public synchronized void setCursiveFontFamily(java.lang.String);
-    method public synchronized void setDatabaseEnabled(boolean);
-    method public deprecated synchronized void setDatabasePath(java.lang.String);
-    method public synchronized void setDefaultFixedFontSize(int);
-    method public synchronized void setDefaultFontSize(int);
-    method public synchronized void setDefaultTextEncodingName(java.lang.String);
-    method public deprecated void setDefaultZoom(android.webkit.WebSettings.ZoomDensity);
-    method public void setDisplayZoomControls(boolean);
-    method public synchronized void setDomStorageEnabled(boolean);
-    method public deprecated void setEnableSmoothTransition(boolean);
-    method public synchronized void setFantasyFontFamily(java.lang.String);
-    method public synchronized void setFixedFontFamily(java.lang.String);
-    method public synchronized void setGeolocationDatabasePath(java.lang.String);
-    method public synchronized void setGeolocationEnabled(boolean);
-    method public synchronized void setJavaScriptCanOpenWindowsAutomatically(boolean);
-    method public synchronized void setJavaScriptEnabled(boolean);
-    method public synchronized void setLayoutAlgorithm(android.webkit.WebSettings.LayoutAlgorithm);
-    method public deprecated void setLightTouchEnabled(boolean);
-    method public void setLoadWithOverviewMode(boolean);
-    method public synchronized void setLoadsImagesAutomatically(boolean);
-    method public void setMediaPlaybackRequiresUserGesture(boolean);
-    method public synchronized void setMinimumFontSize(int);
-    method public synchronized void setMinimumLogicalFontSize(int);
+    method public abstract void setAppCacheEnabled(boolean);
+    method public abstract deprecated void setAppCacheMaxSize(long);
+    method public abstract void setAppCachePath(java.lang.String);
+    method public abstract void setBlockNetworkImage(boolean);
+    method public abstract void setBlockNetworkLoads(boolean);
+    method public abstract void setBuiltInZoomControls(boolean);
+    method public abstract void setCacheMode(int);
+    method public abstract void setCursiveFontFamily(java.lang.String);
+    method public abstract void setDatabaseEnabled(boolean);
+    method public abstract deprecated void setDatabasePath(java.lang.String);
+    method public abstract void setDefaultFixedFontSize(int);
+    method public abstract void setDefaultFontSize(int);
+    method public abstract void setDefaultTextEncodingName(java.lang.String);
+    method public abstract deprecated void setDefaultZoom(android.webkit.WebSettings.ZoomDensity);
+    method public abstract void setDisplayZoomControls(boolean);
+    method public abstract void setDomStorageEnabled(boolean);
+    method public abstract deprecated void setEnableSmoothTransition(boolean);
+    method public abstract void setFantasyFontFamily(java.lang.String);
+    method public abstract void setFixedFontFamily(java.lang.String);
+    method public abstract void setGeolocationDatabasePath(java.lang.String);
+    method public abstract void setGeolocationEnabled(boolean);
+    method public abstract void setJavaScriptCanOpenWindowsAutomatically(boolean);
+    method public abstract void setJavaScriptEnabled(boolean);
+    method public abstract void setLayoutAlgorithm(android.webkit.WebSettings.LayoutAlgorithm);
+    method public abstract deprecated void setLightTouchEnabled(boolean);
+    method public abstract void setLoadWithOverviewMode(boolean);
+    method public abstract void setLoadsImagesAutomatically(boolean);
+    method public abstract void setMediaPlaybackRequiresUserGesture(boolean);
+    method public abstract void setMinimumFontSize(int);
+    method public abstract void setMinimumLogicalFontSize(int);
     method public abstract void setMixedContentMode(int);
-    method public void setNeedInitialFocus(boolean);
-    method public deprecated synchronized void setPluginState(android.webkit.WebSettings.PluginState);
-    method public deprecated synchronized void setRenderPriority(android.webkit.WebSettings.RenderPriority);
-    method public synchronized void setSansSerifFontFamily(java.lang.String);
-    method public void setSaveFormData(boolean);
-    method public deprecated void setSavePassword(boolean);
-    method public synchronized void setSerifFontFamily(java.lang.String);
-    method public synchronized void setStandardFontFamily(java.lang.String);
-    method public synchronized void setSupportMultipleWindows(boolean);
-    method public void setSupportZoom(boolean);
+    method public abstract void setNeedInitialFocus(boolean);
+    method public abstract deprecated void setPluginState(android.webkit.WebSettings.PluginState);
+    method public abstract deprecated void setRenderPriority(android.webkit.WebSettings.RenderPriority);
+    method public abstract void setSansSerifFontFamily(java.lang.String);
+    method public abstract void setSaveFormData(boolean);
+    method public abstract deprecated void setSavePassword(boolean);
+    method public abstract void setSerifFontFamily(java.lang.String);
+    method public abstract void setStandardFontFamily(java.lang.String);
+    method public abstract void setSupportMultipleWindows(boolean);
+    method public abstract void setSupportZoom(boolean);
     method public deprecated synchronized void setTextSize(android.webkit.WebSettings.TextSize);
-    method public synchronized void setTextZoom(int);
-    method public synchronized void setUseWideViewPort(boolean);
-    method public synchronized void setUserAgentString(java.lang.String);
-    method public synchronized boolean supportMultipleWindows();
-    method public boolean supportZoom();
+    method public abstract void setTextZoom(int);
+    method public abstract void setUseWideViewPort(boolean);
+    method public abstract void setUserAgentString(java.lang.String);
+    method public abstract boolean supportMultipleWindows();
+    method public abstract boolean supportZoom();
     field public static final int LOAD_CACHE_ELSE_NETWORK = 1; // 0x1
     field public static final int LOAD_CACHE_ONLY = 3; // 0x3
     field public static final int LOAD_DEFAULT = -1; // 0xffffffff
@@ -36492,14 +36499,15 @@
     field public static final int ERROR_UNSUPPORTED_SCHEME = -10; // 0xfffffff6
   }
 
-  public class WebViewDatabase {
-    method public void clearFormData();
-    method public void clearHttpAuthUsernamePassword();
-    method public deprecated void clearUsernamePassword();
+  public abstract class WebViewDatabase {
+    ctor public WebViewDatabase();
+    method public abstract void clearFormData();
+    method public abstract void clearHttpAuthUsernamePassword();
+    method public abstract deprecated void clearUsernamePassword();
     method public static android.webkit.WebViewDatabase getInstance(android.content.Context);
-    method public boolean hasFormData();
-    method public boolean hasHttpAuthUsernamePassword();
-    method public deprecated boolean hasUsernamePassword();
+    method public abstract boolean hasFormData();
+    method public abstract boolean hasHttpAuthUsernamePassword();
+    method public abstract deprecated boolean hasUsernamePassword();
   }
 
   public class WebViewFragment extends android.app.Fragment {
diff --git a/core/java/android/net/WebAddress.java b/core/java/android/net/WebAddress.java
index 8126b75..24d4eb8 100644
--- a/core/java/android/net/WebAddress.java
+++ b/core/java/android/net/WebAddress.java
@@ -18,6 +18,8 @@
 
 import static android.util.Patterns.GOOD_IRI_CHAR;
 
+import android.annotation.SystemApi;
+
 import java.util.Locale;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
@@ -38,6 +40,9 @@
  * If given an https scheme but no port, fills in port
  *
  */
+// TODO(igsolla): remove WebAddress from the system SDK once the WebView apk does not
+// longer need to be binary compatible with the API 21 version of the framework.
+@SystemApi
 public class WebAddress {
 
     private String mScheme;
@@ -136,42 +141,52 @@
         return mScheme + "://" + authInfo + mHost + port + mPath;
     }
 
+    /** {@hide} */
     public void setScheme(String scheme) {
       mScheme = scheme;
     }
 
+    /** {@hide} */
     public String getScheme() {
       return mScheme;
     }
 
+    /** {@hide} */
     public void setHost(String host) {
       mHost = host;
     }
 
+    /** {@hide} */
     public String getHost() {
       return mHost;
     }
 
+    /** {@hide} */
     public void setPort(int port) {
       mPort = port;
     }
 
+    /** {@hide} */
     public int getPort() {
       return mPort;
     }
 
+    /** {@hide} */
     public void setPath(String path) {
       mPath = path;
     }
 
+    /** {@hide} */
     public String getPath() {
       return mPath;
     }
 
+    /** {@hide} */
     public void setAuthInfo(String authInfo) {
       mAuthInfo = authInfo;
     }
 
+    /** {@hide} */
     public String getAuthInfo() {
       return mAuthInfo;
     }
diff --git a/core/java/android/webkit/CookieManager.java b/core/java/android/webkit/CookieManager.java
index 20ef646..eca96f9 100644
--- a/core/java/android/webkit/CookieManager.java
+++ b/core/java/android/webkit/CookieManager.java
@@ -16,18 +16,14 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.net.WebAddress;
 
 /**
  * Manages the cookies used by an application's {@link WebView} instances.
  * Cookies are manipulated according to RFC2109.
  */
-public class CookieManager {
-    /**
-     * @hide Only for use by WebViewProvider implementations
-     */
-    protected CookieManager() {
-    }
+public abstract class CookieManager {
 
     @Override
     protected Object clone() throws CloneNotSupportedException {
@@ -59,9 +55,7 @@
      * @param accept whether {@link WebView} instances should send and accept
      *               cookies
      */
-    public synchronized void setAcceptCookie(boolean accept) {
-        throw new MustOverrideException();
-    }
+    public abstract void setAcceptCookie(boolean accept);
 
     /**
      * Gets whether the application's {@link WebView} instances send and accept
@@ -69,9 +63,7 @@
      *
      * @return true if {@link WebView} instances send and accept cookies
      */
-    public synchronized boolean acceptCookie() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean acceptCookie();
 
    /**
      * Sets whether the {@link WebView} should allow third party cookies to be set.
@@ -87,9 +79,7 @@
      * @param accept whether the {@link WebView} instance should accept
      *               third party cookies
      */
-    public void setAcceptThirdPartyCookies(WebView webview, boolean accept) {
-        throw new MustOverrideException();
-    }
+    public abstract void setAcceptThirdPartyCookies(WebView webview, boolean accept);
 
     /**
      * Gets whether the {@link WebView} should allow third party cookies to be set.
@@ -97,9 +87,7 @@
      * @param webview the {@link WebView} instance to get the cookie policy for
      * @return true if the {@link WebView} accepts third party cookies
      */
-    public boolean acceptThirdPartyCookies(WebView webview) {
-        throw new MustOverrideException();
-    }
+    public abstract boolean acceptThirdPartyCookies(WebView webview);
 
     /**
      * Sets a cookie for the given URL. Any existing cookie with the same host,
@@ -110,9 +98,7 @@
      * @param value the cookie as a string, using the format of the 'Set-Cookie'
      *              HTTP response header
      */
-    public void setCookie(String url, String value) {
-        throw new MustOverrideException();
-    }
+    public abstract void setCookie(String url, String value);
 
     /**
      * Sets a cookie for the given URL. Any existing cookie with the same host,
@@ -133,9 +119,7 @@
      *              HTTP response header
      * @param callback a callback to be executed when the cookie has been set
      */
-    public void setCookie(String url, String value, ValueCallback<Boolean> callback) {
-        throw new MustOverrideException();
-    }
+    public abstract void setCookie(String url, String value, ValueCallback<Boolean> callback);
 
     /**
      * Gets the cookies for the given URL.
@@ -144,9 +128,7 @@
      * @return value the cookies as a string, using the format of the 'Cookie'
      *               HTTP request header
      */
-    public String getCookie(String url) {
-        throw new MustOverrideException();
-    }
+    public abstract String getCookie(String url);
 
     /**
      * See {@link #getCookie(String)}.
@@ -155,11 +137,10 @@
      * @param privateBrowsing whether to use the private browsing cookie jar
      * @return value the cookies as a string, using the format of the 'Cookie'
      *               HTTP request header
-     * @hide Used by Browser, no intention to publish.
+     * @hide Used by Browser and by WebViewProvider implementations.
      */
-    public String getCookie(String url, boolean privateBrowsing) {
-        throw new MustOverrideException();
-    }
+    @SystemApi
+    public abstract String getCookie(String url, boolean privateBrowsing);
 
     /**
      * Gets cookie(s) for a given uri so that it can be set to "cookie:" in http
@@ -168,10 +149,11 @@
      * @param uri the WebAddress for which the cookies are requested
      * @return value the cookies as a string, using the format of the 'Cookie'
      *               HTTP request header
-     * @hide Used by RequestHandle, no intention to publish.
+     * @hide Used by RequestHandle and by WebViewProvider implementations.
      */
+    @SystemApi
     public synchronized String getCookie(WebAddress uri) {
-        throw new MustOverrideException();
+        return getCookie(uri.toString());
     }
 
     /**
@@ -179,9 +161,7 @@
      * date.
      * @deprecated use {@link #removeSessionCookies(ValueCallback)} instead.
      */
-    public void removeSessionCookie() {
-        throw new MustOverrideException();
-    }
+    public abstract void removeSessionCookie();
 
     /**
      * Removes all session cookies, which are cookies without an expiration
@@ -197,18 +177,14 @@
      * method from a thread without a Looper.
      * @param callback a callback which is executed when the session cookies have been removed
      */
-    public void removeSessionCookies(ValueCallback<Boolean> callback) {
-        throw new MustOverrideException();
-    }
+    public abstract void removeSessionCookies(ValueCallback<Boolean> callback);
 
     /**
      * Removes all cookies.
      * @deprecated Use {@link #removeAllCookies(ValueCallback)} instead.
      */
     @Deprecated
-    public void removeAllCookie() {
-        throw new MustOverrideException();
-    }
+    public abstract void removeAllCookie();
 
     /**
      * Removes all cookies.
@@ -223,54 +199,37 @@
      * method from a thread without a Looper.
      * @param callback a callback which is executed when the cookies have been removed
      */
-    public void removeAllCookies(ValueCallback<Boolean> callback) {
-        throw new MustOverrideException();
-    }
+    public abstract void removeAllCookies(ValueCallback<Boolean> callback);
 
     /**
      * Gets whether there are stored cookies.
      *
      * @return true if there are stored cookies
      */
-    public synchronized boolean hasCookies() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean hasCookies();
 
     /**
      * See {@link #hasCookies()}.
      *
      * @param privateBrowsing whether to use the private browsing cookie jar
-     * @hide Used by Browser, no intention to publish.
+     * @hide Used by Browser and WebViewProvider implementations.
      */
-    public synchronized boolean hasCookies(boolean privateBrowsing) {
-        throw new MustOverrideException();
-    }
+    @SystemApi
+    public abstract boolean hasCookies(boolean privateBrowsing);
 
     /**
      * Removes all expired cookies.
      * @deprecated The WebView handles removing expired cookies automatically.
      */
     @Deprecated
-    public void removeExpiredCookie() {
-        throw new MustOverrideException();
-    }
+    public abstract void removeExpiredCookie();
 
     /**
      * Ensures all cookies currently accessible through the getCookie API are
      * written to persistent storage.
      * This call will block the caller until it is done and may perform I/O.
      */
-    public void flush() {
-        flushCookieStore();
-    }
-
-    /**
-     * Flushes all cookies managed by the Chrome HTTP stack to flash.
-     *
-     * @hide Package level api, called from CookieSyncManager
-     */
-    protected void flushCookieStore() {
-    }
+    public abstract void flush();
 
     /**
      * Gets whether the application's {@link WebView} instances send and accept
@@ -289,9 +248,8 @@
      *
      * @hide Only for use by WebViewProvider implementations
      */
-    protected boolean allowFileSchemeCookiesImpl() {
-        throw new MustOverrideException();
-    }
+    @SystemApi
+    protected abstract boolean allowFileSchemeCookiesImpl();
 
     /**
      * Sets whether the application's {@link WebView} instances should send and
@@ -314,7 +272,6 @@
      *
      * @hide Only for use by WebViewProvider implementations
      */
-    protected void setAcceptFileSchemeCookiesImpl(boolean accept) {
-        throw new MustOverrideException();
-    }
+    @SystemApi
+    protected abstract void setAcceptFileSchemeCookiesImpl(boolean accept);
 }
diff --git a/core/java/android/webkit/DebugFlags.java b/core/java/android/webkit/DebugFlags.java
deleted file mode 100644
index 7b3cb1b..0000000
--- a/core/java/android/webkit/DebugFlags.java
+++ /dev/null
@@ -1,37 +0,0 @@
-/*
- * Copyright (C) 2009 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package android.webkit;
-
-/**
- * This class is a container for all of the debug flags used in the Java
- * components of webkit.  These flags must be final in order to ensure that
- * the compiler optimizes the code that uses them out of the final executable.
- *
- * The name of each flags maps directly to the name of the class in which that
- * flag is used.
- *
- * @hide Only used by WebView implementations.
- */
-public class DebugFlags {
-
-    public static final boolean COOKIE_SYNC_MANAGER = false;
-    public static final boolean TRACE_API = false;
-    public static final boolean TRACE_CALLBACK = false;
-    public static final boolean URL_UTIL = false;
-    public static final boolean WEB_SYNC_MANAGER = false;
-
-}
diff --git a/core/java/android/webkit/FindActionModeCallback.java b/core/java/android/webkit/FindActionModeCallback.java
index c68b450..ab6a2f9 100644
--- a/core/java/android/webkit/FindActionModeCallback.java
+++ b/core/java/android/webkit/FindActionModeCallback.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Point;
@@ -36,6 +37,7 @@
 /**
  * @hide
  */
+@SystemApi
 public class FindActionModeCallback implements ActionMode.Callback, TextWatcher,
         View.OnClickListener, WebView.FindListener {
     private View mCustomView;
diff --git a/core/java/android/webkit/GeolocationPermissions.java b/core/java/android/webkit/GeolocationPermissions.java
index bc3d035..7187f22 100644
--- a/core/java/android/webkit/GeolocationPermissions.java
+++ b/core/java/android/webkit/GeolocationPermissions.java
@@ -16,6 +16,8 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
+
 import java.util.Set;
 
 /**
@@ -136,5 +138,6 @@
      * way to call createHandler() and createUIHandler(), so it would not work).
      * @hide Only for use by WebViewProvider implementations
      */
+    @SystemApi
     public GeolocationPermissions() {}
 }
diff --git a/core/java/android/webkit/HttpAuthHandler.java b/core/java/android/webkit/HttpAuthHandler.java
index ee3b3698..45fc1f5 100644
--- a/core/java/android/webkit/HttpAuthHandler.java
+++ b/core/java/android/webkit/HttpAuthHandler.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.os.Handler;
 
 /**
@@ -30,6 +31,7 @@
     /**
      * @hide Only for use by WebViewProvider implementations.
      */
+    @SystemApi
     public HttpAuthHandler() {
     }
 
diff --git a/core/java/android/webkit/JsDialogHelper.java b/core/java/android/webkit/JsDialogHelper.java
index bb0339e..cc475c3 100644
--- a/core/java/android/webkit/JsDialogHelper.java
+++ b/core/java/android/webkit/JsDialogHelper.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.app.Activity;
 import android.app.AlertDialog;
 import android.content.Context;
@@ -34,8 +35,9 @@
  * Helper class to create JavaScript dialogs. It is used by
  * different WebView implementations.
  *
- * @hide Helper class for internal use
+ * @hide
  */
+@SystemApi
 public class JsDialogHelper {
 
     private static final String TAG = "JsDialogHelper";
diff --git a/core/java/android/webkit/JsPromptResult.java b/core/java/android/webkit/JsPromptResult.java
index a1bf124..771cc32 100644
--- a/core/java/android/webkit/JsPromptResult.java
+++ b/core/java/android/webkit/JsPromptResult.java
@@ -16,6 +16,8 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
+
 
 /**
  * Public class for handling JavaScript prompt requests. The WebChromeClient will receive a
@@ -39,6 +41,7 @@
     /**
      * @hide Only for use by WebViewProvider implementations
      */
+    @SystemApi
     public JsPromptResult(ResultReceiver receiver) {
         super(receiver);
     }
@@ -46,6 +49,7 @@
     /**
      * @hide Only for use by WebViewProvider implementations
      */
+    @SystemApi
     public String getStringResult() {
         return mStringResult;
     }
diff --git a/core/java/android/webkit/JsResult.java b/core/java/android/webkit/JsResult.java
index e4e6851..d36ab418 100644
--- a/core/java/android/webkit/JsResult.java
+++ b/core/java/android/webkit/JsResult.java
@@ -16,6 +16,8 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
+
 /**
  * An instance of this class is passed as a parameter in various {@link WebChromeClient} action
  * notifications. The object is used as a handle onto the underlying JavaScript-originated request,
@@ -27,6 +29,7 @@
      * notifications when the JavaScript result represented by a JsResult instance has
      * @hide Only for use by WebViewProvider implementations
      */
+    @SystemApi
     public interface ResultReceiver {
         public void onJsResultComplete(JsResult result);
     }
@@ -54,6 +57,7 @@
     /**
      * @hide Only for use by WebViewProvider implementations
      */
+    @SystemApi
     public JsResult(ResultReceiver receiver) {
         mReceiver = receiver;
     }
@@ -61,6 +65,7 @@
     /**
      * @hide Only for use by WebViewProvider implementations
      */
+    @SystemApi
     public final boolean getResult() {
         return mResult;
     }
diff --git a/core/java/android/webkit/MustOverrideException.java b/core/java/android/webkit/MustOverrideException.java
deleted file mode 100644
index 0643bf0..0000000
--- a/core/java/android/webkit/MustOverrideException.java
+++ /dev/null
@@ -1,25 +0,0 @@
-/*
- * Copyright (C) 2012 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package android.webkit;
-
-// TODO: Remove MustOverrideException and make all methods throwing it abstract instead;
-// needs API file update.
-class MustOverrideException extends RuntimeException {
-    MustOverrideException() {
-        super("abstract function called: must be overriden!");
-    }
-}
\ No newline at end of file
diff --git a/core/java/android/webkit/SslErrorHandler.java b/core/java/android/webkit/SslErrorHandler.java
index af31544..537065d 100644
--- a/core/java/android/webkit/SslErrorHandler.java
+++ b/core/java/android/webkit/SslErrorHandler.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.os.Handler;
 
 /**
@@ -30,6 +31,7 @@
     /**
      * @hide Only for use by WebViewProvider implementations.
      */
+    @SystemApi
     public SslErrorHandler() {}
 
     /**
diff --git a/core/java/android/webkit/URLUtil.java b/core/java/android/webkit/URLUtil.java
index d115984..f5233b6 100644
--- a/core/java/android/webkit/URLUtil.java
+++ b/core/java/android/webkit/URLUtil.java
@@ -29,6 +29,7 @@
 public final class URLUtil {
 
     private static final String LOGTAG = "webkit";
+    private static final boolean TRACE = false;
 
     // to refer to bar.png under your package's asset/foo/ directory, use
     // "file:///android_asset/foo/bar.png".
@@ -49,7 +50,7 @@
         String retVal = inUrl;
         WebAddress webAddress;
 
-        if (DebugFlags.URL_UTIL) Log.v(LOGTAG, "guessURL before queueRequest: " + inUrl);
+        if (TRACE) Log.v(LOGTAG, "guessURL before queueRequest: " + inUrl);
 
         if (inUrl.length() == 0) return inUrl;
         if (inUrl.startsWith("about:")) return inUrl;
@@ -69,7 +70,7 @@
             webAddress = new WebAddress(inUrl);
         } catch (ParseException ex) {
 
-            if (DebugFlags.URL_UTIL) {
+            if (TRACE) {
                 Log.v(LOGTAG, "smartUrlFilter: failed to parse url = " + inUrl);
             }
             return retVal;
@@ -286,7 +287,7 @@
         }
         return url;
     }
-    
+
     /**
      * Guesses canonical filename that a download would have, using
      * the URL and contentDisposition. File extension, if not defined,
@@ -294,7 +295,7 @@
      * @param url Url to the content
      * @param contentDisposition Content-Disposition HTTP header or null
      * @param mimeType Mime-type of the content or null
-     * 
+     *
      * @return suggested filename
      */
     public static final String guessFileName(
diff --git a/core/java/android/webkit/WebBackForwardList.java b/core/java/android/webkit/WebBackForwardList.java
index bfef2e7..e671376 100644
--- a/core/java/android/webkit/WebBackForwardList.java
+++ b/core/java/android/webkit/WebBackForwardList.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import java.io.Serializable;
 
 /**
@@ -23,56 +24,38 @@
  * WebView.copyBackForwardList() will return a copy of this class used to
  * inspect the entries in the list.
  */
-public class WebBackForwardList implements Cloneable, Serializable {
-
-    /**
-     *  @hide
-     */
-    public WebBackForwardList() {
-    }
-
+public abstract class WebBackForwardList implements Cloneable, Serializable {
     /**
      * Return the current history item. This method returns null if the list is
      * empty.
      * @return The current history item.
      */
-    public synchronized WebHistoryItem getCurrentItem() {
-        throw new MustOverrideException();
-    }
+    public abstract WebHistoryItem getCurrentItem();
 
     /**
      * Get the index of the current history item. This index can be used to
      * directly index into the array list.
      * @return The current index from 0...n or -1 if the list is empty.
      */
-    public synchronized int getCurrentIndex() {
-        throw new MustOverrideException();
-    }
+    public abstract int getCurrentIndex();
 
     /**
      * Get the history item at the given index. The index range is from 0...n
      * where 0 is the first item and n is the last item.
      * @param index The index to retrieve.
      */
-    public synchronized WebHistoryItem getItemAtIndex(int index) {
-        throw new MustOverrideException();
-    }
+    public abstract WebHistoryItem getItemAtIndex(int index);
 
     /**
      * Get the total size of the back/forward list.
      * @return The size of the list.
      */
-    public synchronized int getSize() {
-        throw new MustOverrideException();
-    }
+    public abstract int getSize();
 
     /**
      * Clone the entire object to be used in the UI thread by clients of
      * WebView. This creates a copy that should never be modified by any of the
      * webkit package classes.
      */
-    protected synchronized WebBackForwardList clone() {
-        throw new MustOverrideException();
-    }
-
+    protected abstract WebBackForwardList clone();
 }
diff --git a/core/java/android/webkit/WebChromeClient.java b/core/java/android/webkit/WebChromeClient.java
index 46a7fd0..768dc9f 100644
--- a/core/java/android/webkit/WebChromeClient.java
+++ b/core/java/android/webkit/WebChromeClient.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.content.Intent;
 import android.content.pm.ActivityInfo;
 import android.graphics.Bitmap;
@@ -509,6 +510,7 @@
      * @deprecated Use {@link #showFileChooser} instead.
      * @hide This method was not published in any SDK version.
      */
+    @SystemApi
     @Deprecated
     public void openFileChooser(ValueCallback<Uri> uploadFile, String acceptType, String capture) {
         uploadFile.onReceiveValue(null);
diff --git a/core/java/android/webkit/WebHistoryItem.java b/core/java/android/webkit/WebHistoryItem.java
index 9a588e4..569fccd 100644
--- a/core/java/android/webkit/WebHistoryItem.java
+++ b/core/java/android/webkit/WebHistoryItem.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.graphics.Bitmap;
 
 /**
@@ -24,14 +25,7 @@
  * item. Each history item may be updated during the load of a page.
  * @see WebBackForwardList
  */
-public class WebHistoryItem implements Cloneable {
-
-    /**
-     * @hide
-     */
-    public WebHistoryItem() {
-    }
-
+public abstract class WebHistoryItem implements Cloneable {
     /**
      * Return an identifier for this history item. If an item is a copy of
      * another item, the identifiers will be the same even if they are not the
@@ -40,10 +34,9 @@
      * @deprecated This method is now obsolete.
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
+    @SystemApi
     @Deprecated
-    public int getId() {
-        throw new MustOverrideException();
-    }
+    public abstract int getId();
 
     /**
      * Return the url of this history item. The url is the base url of this
@@ -53,29 +46,23 @@
      * Note: The VM ensures 32-bit atomic read/write operations so we don't have
      * to synchronize this method.
      */
-    public String getUrl() {
-        throw new MustOverrideException();
-    }
+    public abstract String getUrl();
 
     /**
      * Return the original url of this history item. This was the requested
-     * url, the final url may be different as there might have been 
+     * url, the final url may be different as there might have been
      * redirects while loading the site.
      * @return The original url of this history item.
      */
-    public String getOriginalUrl() {
-        throw new MustOverrideException();
-    }
-    
+    public abstract String getOriginalUrl();
+
     /**
      * Return the document title of this history item.
      * @return The document title of this history item.
      * Note: The VM ensures 32-bit atomic read/write operations so we don't have
      * to synchronize this method.
      */
-    public String getTitle() {
-        throw new MustOverrideException();
-    }
+    public abstract String getTitle();
 
     /**
      * Return the favicon of this history item or null if no favicon was found.
@@ -83,15 +70,10 @@
      * Note: The VM ensures 32-bit atomic read/write operations so we don't have
      * to synchronize this method.
      */
-    public Bitmap getFavicon() {
-        throw new MustOverrideException();
-    }
+    public abstract Bitmap getFavicon();
 
     /**
      * Clone the history item for use by clients of WebView.
      */
-    protected synchronized WebHistoryItem clone() {
-        throw new MustOverrideException();
-    }
-
+    protected abstract WebHistoryItem clone();
 }
diff --git a/core/java/android/webkit/WebIconDatabase.java b/core/java/android/webkit/WebIconDatabase.java
index e574593..08956e0 100644
--- a/core/java/android/webkit/WebIconDatabase.java
+++ b/core/java/android/webkit/WebIconDatabase.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.content.ContentResolver;
 import android.graphics.Bitmap;
 
@@ -32,7 +33,7 @@
  *             up to {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR2}
  */
 @Deprecated
-public class WebIconDatabase {
+public abstract class WebIconDatabase {
     /**
      * Interface for receiving icons from the database.
      * @deprecated This interface is obsolete.
@@ -52,23 +53,17 @@
      * Open a the icon database and store the icons in the given path.
      * @param path The directory path where the icon database will be stored.
      */
-    public void open(String path) {
-        throw new MustOverrideException();
-    }
+    public abstract void open(String path);
 
     /**
      * Close the shared instance of the icon database.
      */
-    public void close() {
-        throw new MustOverrideException();
-    }
+    public abstract void close();
 
     /**
      * Removes all the icons in the database.
      */
-    public void removeAllIcons() {
-        throw new MustOverrideException();
-    }
+    public abstract void removeAllIcons();
 
     /**
      * Request the Bitmap representing the icon for the given page
@@ -76,32 +71,25 @@
      * @param url The page's url.
      * @param listener An implementation on IconListener to receive the result.
      */
-    public void requestIconForPageUrl(String url, IconListener listener) {
-        throw new MustOverrideException();
-    }
+    public abstract void requestIconForPageUrl(String url, IconListener listener);
 
     /** {@hide}
      */
-    public void bulkRequestIconForPageUrl(ContentResolver cr, String where,
-            IconListener listener) {
-        throw new MustOverrideException();
-    }
+    @SystemApi
+    public abstract void bulkRequestIconForPageUrl(ContentResolver cr, String where,
+            IconListener listener);
 
     /**
      * Retain the icon for the given page url.
      * @param url The page's url.
      */
-    public void retainIconForPageUrl(String url) {
-        throw new MustOverrideException();
-    }
+    public abstract void retainIconForPageUrl(String url);
 
     /**
      * Release the icon for the given page url.
      * @param url The page's url.
      */
-    public void releaseIconForPageUrl(String url) {
-        throw new MustOverrideException();
-    }
+    public abstract void releaseIconForPageUrl(String url);
 
     /**
      * Get the global instance of WebIconDatabase.
@@ -113,9 +101,4 @@
         // XXX: Must be created in the UI thread.
         return WebViewFactory.getProvider().getWebIconDatabase();
     }
-
-    /**
-     * @hide Only for use by WebViewProvider implementations
-     */
-    protected WebIconDatabase() {}
 }
diff --git a/core/java/android/webkit/WebSettings.java b/core/java/android/webkit/WebSettings.java
index 7cf3cb5..1d2c311 100644
--- a/core/java/android/webkit/WebSettings.java
+++ b/core/java/android/webkit/WebSettings.java
@@ -204,25 +204,15 @@
     public static final int MIXED_CONTENT_COMPATIBILITY_MODE = 2;
 
     /**
-     * Hidden constructor to prevent clients from creating a new settings
-     * instance or deriving the class.
-     *
-     * @hide
-     */
-    protected WebSettings() {
-    }
-
-    /**
      * Enables dumping the pages navigation cache to a text file. The default
      * is false.
      *
      * @deprecated This method is now obsolete.
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
+    @SystemApi
     @Deprecated
-    public void setNavDump(boolean enabled) {
-        throw new MustOverrideException();
-    }
+    public abstract void setNavDump(boolean enabled);
 
     /**
      * Gets whether dumping the navigation cache is enabled.
@@ -232,10 +222,9 @@
      * @deprecated This method is now obsolete.
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
+    @SystemApi
     @Deprecated
-    public boolean getNavDump() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getNavDump();
 
     /**
      * Sets whether the WebView should support zooming using its on-screen zoom
@@ -246,9 +235,7 @@
      *
      * @param support whether the WebView should support zoom
      */
-    public void setSupportZoom(boolean support) {
-        throw new MustOverrideException();
-    }
+    public abstract void setSupportZoom(boolean support);
 
     /**
      * Gets whether the WebView supports zoom.
@@ -256,9 +243,7 @@
      * @return true if the WebView supports zoom
      * @see #setSupportZoom
      */
-    public boolean supportZoom() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean supportZoom();
 
     /**
      * Sets whether the WebView requires a user gesture to play media.
@@ -266,9 +251,7 @@
      *
      * @param require whether the WebView requires a user gesture to play media
      */
-    public void setMediaPlaybackRequiresUserGesture(boolean require) {
-        throw new MustOverrideException();
-    }
+    public abstract void setMediaPlaybackRequiresUserGesture(boolean require);
 
     /**
      * Gets whether the WebView requires a user gesture to play media.
@@ -276,9 +259,7 @@
      * @return true if the WebView requires a user gesture to play media
      * @see #setMediaPlaybackRequiresUserGesture
      */
-    public boolean getMediaPlaybackRequiresUserGesture() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getMediaPlaybackRequiresUserGesture();
 
     /**
      * Sets whether the WebView should use its built-in zoom mechanisms. The
@@ -295,9 +276,7 @@
     // This method was intended to select between the built-in zoom mechanisms
     // and the separate zoom controls. The latter were obtained using
     // {@link WebView#getZoomControls}, which is now hidden.
-    public void setBuiltInZoomControls(boolean enabled) {
-        throw new MustOverrideException();
-    }
+    public abstract void setBuiltInZoomControls(boolean enabled);
 
     /**
      * Gets whether the zoom mechanisms built into WebView are being used.
@@ -305,9 +284,7 @@
      * @return true if the zoom mechanisms built into WebView are being used
      * @see #setBuiltInZoomControls
      */
-    public boolean getBuiltInZoomControls() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getBuiltInZoomControls();
 
     /**
      * Sets whether the WebView should display on-screen zoom controls when
@@ -316,9 +293,7 @@
      *
      * @param enabled whether the WebView should display on-screen zoom controls
      */
-    public void setDisplayZoomControls(boolean enabled) {
-        throw new MustOverrideException();
-    }
+    public abstract void setDisplayZoomControls(boolean enabled);
 
     /**
      * Gets whether the WebView displays on-screen zoom controls when using
@@ -328,9 +303,7 @@
      *         the built-in zoom mechanisms
      * @see #setDisplayZoomControls
      */
-    public boolean getDisplayZoomControls() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getDisplayZoomControls();
 
     /**
      * Enables or disables file access within WebView. File access is enabled by
@@ -338,36 +311,28 @@
      * Assets and resources are still accessible using file:///android_asset and
      * file:///android_res.
      */
-    public void setAllowFileAccess(boolean allow) {
-        throw new MustOverrideException();
-    }
+    public abstract void setAllowFileAccess(boolean allow);
 
     /**
      * Gets whether this WebView supports file access.
      *
      * @see #setAllowFileAccess
      */
-    public boolean getAllowFileAccess() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getAllowFileAccess();
 
     /**
      * Enables or disables content URL access within WebView.  Content URL
      * access allows WebView to load content from a content provider installed
      * in the system. The default is enabled.
      */
-    public void setAllowContentAccess(boolean allow) {
-        throw new MustOverrideException();
-    }
+    public abstract void setAllowContentAccess(boolean allow);
 
     /**
      * Gets whether this WebView supports content URL access.
      *
      * @see #setAllowContentAccess
      */
-    public boolean getAllowContentAccess() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getAllowContentAccess();
 
     /**
      * Sets whether the WebView loads pages in overview mode, that is,
@@ -376,9 +341,7 @@
      * of the WebView control, for example, when {@link #getUseWideViewPort}
      * is enabled. The default is false.
      */
-    public void setLoadWithOverviewMode(boolean overview) {
-        throw new MustOverrideException();
-    }
+    public abstract void setLoadWithOverviewMode(boolean overview);
 
     /**
      * Gets whether this WebView loads pages in overview mode.
@@ -386,9 +349,7 @@
      * @return whether this WebView loads pages in overview mode
      * @see #setLoadWithOverviewMode
      */
-    public boolean getLoadWithOverviewMode() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getLoadWithOverviewMode();
 
     /**
      * Sets whether the WebView will enable smooth transition while panning or
@@ -400,9 +361,7 @@
      * @deprecated This method is now obsolete, and will become a no-op in future.
      */
     @Deprecated
-    public void setEnableSmoothTransition(boolean enable) {
-        throw new MustOverrideException();
-    }
+    public abstract void setEnableSmoothTransition(boolean enable);
 
     /**
      * Gets whether the WebView enables smooth transition while panning or
@@ -413,9 +372,7 @@
      * @deprecated This method is now obsolete, and will become a no-op in future.
      */
     @Deprecated
-    public boolean enableSmoothTransition() {
-        throw new MustOverrideException();
-    }
+    public abstract  boolean enableSmoothTransition();
 
     /**
      * Sets whether the WebView uses its background for over scroll background.
@@ -425,10 +382,9 @@
      * @deprecated This method is now obsolete.
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
+    @SystemApi
     @Deprecated
-    public void setUseWebViewBackgroundForOverscrollBackground(boolean view) {
-        throw new MustOverrideException();
-    }
+    public abstract  void setUseWebViewBackgroundForOverscrollBackground(boolean view);
 
     /**
      * Gets whether this WebView uses WebView's background instead of
@@ -438,17 +394,14 @@
      * @deprecated This method is now obsolete.
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
+    @SystemApi
     @Deprecated
-    public boolean getUseWebViewBackgroundForOverscrollBackground() {
-        throw new MustOverrideException();
-    }
+    public abstract  boolean getUseWebViewBackgroundForOverscrollBackground();
 
     /**
      * Sets whether the WebView should save form data. The default is true.
      */
-    public void setSaveFormData(boolean save) {
-        throw new MustOverrideException();
-    }
+    public abstract  void setSaveFormData(boolean save);
 
     /**
      * Gets whether the WebView saves form data.
@@ -456,18 +409,14 @@
      * @return whether the WebView saves form data
      * @see #setSaveFormData
      */
-    public boolean getSaveFormData() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getSaveFormData();
 
     /**
      * Sets whether the WebView should save passwords. The default is true.
      * @deprecated Saving passwords in WebView will not be supported in future versions.
      */
     @Deprecated
-    public void setSavePassword(boolean save) {
-        throw new MustOverrideException();
-    }
+    public abstract void setSavePassword(boolean save);
 
     /**
      * Gets whether the WebView saves passwords.
@@ -477,18 +426,14 @@
      * @deprecated Saving passwords in WebView will not be supported in future versions.
      */
     @Deprecated
-    public boolean getSavePassword() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getSavePassword();
 
     /**
      * Sets the text zoom of the page in percent. The default is 100.
      *
      * @param textZoom the text zoom in percent
      */
-    public synchronized void setTextZoom(int textZoom) {
-        throw new MustOverrideException();
-    }
+    public abstract void setTextZoom(int textZoom);
 
     /**
      * Gets the text zoom of the page in percent.
@@ -496,27 +441,23 @@
      * @return the text zoom of the page in percent
      * @see #setTextZoom
      */
-    public synchronized int getTextZoom() {
-        throw new MustOverrideException();
-    }
+    public abstract int getTextZoom();
 
     /**
      * Sets policy for third party cookies.
      * Developers should access this via {@link CookieManager#setShouldAcceptThirdPartyCookies}.
      * @hide Internal API.
      */
-    public void setAcceptThirdPartyCookies(boolean accept) {
-        throw new MustOverrideException();
-    }
+    @SystemApi
+    public abstract void setAcceptThirdPartyCookies(boolean accept);
 
     /**
      * Gets policy for third party cookies.
      * Developers should access this via {@link CookieManager#getShouldAcceptThirdPartyCookies}.
      * @hide Internal API
      */
-    public boolean getAcceptThirdPartyCookies() {
-        throw new MustOverrideException();
-    }
+    @SystemApi
+    public abstract boolean getAcceptThirdPartyCookies();
 
     /**
      * Sets the text size of the page. The default is {@link TextSize#NORMAL}.
@@ -569,9 +510,7 @@
      *             recommended alternatives.
      */
     @Deprecated
-    public void setDefaultZoom(ZoomDensity zoom) {
-        throw new MustOverrideException();
-    }
+    public abstract void setDefaultZoom(ZoomDensity zoom);
 
     /**
      * Gets the default zoom density of the page. This should be called from
@@ -583,9 +522,7 @@
      * @see #setDefaultZoom
      * @deprecated Will only return the default value.
      */
-    public ZoomDensity getDefaultZoom() {
-        throw new MustOverrideException();
-    }
+    public abstract ZoomDensity getDefaultZoom();
 
     /**
      * Enables using light touches to make a selection and activate mouseovers.
@@ -593,9 +530,7 @@
      *             setting is obsolete and has no effect.
      */
     @Deprecated
-    public void setLightTouchEnabled(boolean enabled) {
-        throw new MustOverrideException();
-    }
+    public abstract void setLightTouchEnabled(boolean enabled);
 
     /**
      * Gets whether light touches are enabled.
@@ -603,9 +538,7 @@
      * @deprecated This setting is obsolete.
      */
     @Deprecated
-    public boolean getLightTouchEnabled() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getLightTouchEnabled();
 
     /**
      * Controlled a rendering optimization that is no longer present. Setting
@@ -615,7 +548,7 @@
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
     @Deprecated
-    public synchronized void setUseDoubleTree(boolean use) {
+    public void setUseDoubleTree(boolean use) {
         // Specified to do nothing, so no need for derived classes to override.
     }
 
@@ -627,7 +560,7 @@
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
     @Deprecated
-    public synchronized boolean getUseDoubleTree() {
+    public boolean getUseDoubleTree() {
         // Returns false unconditionally, so no need for derived classes to override.
         return false;
     }
@@ -645,10 +578,9 @@
      * @deprecated Please use {@link #setUserAgentString} instead.
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
+    @SystemApi
     @Deprecated
-    public synchronized void setUserAgent(int ua) {
-        throw new MustOverrideException();
-    }
+    public abstract void setUserAgent(int ua);
 
     /**
      * Gets the user-agent as an integer code.
@@ -664,10 +596,9 @@
      * @deprecated Please use {@link #getUserAgentString} instead.
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
+    @SystemApi
     @Deprecated
-    public synchronized int getUserAgent() {
-        throw new MustOverrideException();
-    }
+    public abstract int getUserAgent();
 
     /**
      * Sets whether the WebView should enable support for the &quot;viewport&quot;
@@ -680,9 +611,7 @@
      *
      * @param use whether to enable support for the viewport meta tag
      */
-    public synchronized void setUseWideViewPort(boolean use) {
-        throw new MustOverrideException();
-    }
+    public abstract void setUseWideViewPort(boolean use);
 
     /**
      * Gets whether the WebView supports the &quot;viewport&quot;
@@ -691,9 +620,7 @@
      * @return true if the WebView supports the viewport meta tag
      * @see #setUseWideViewPort
      */
-    public synchronized boolean getUseWideViewPort() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getUseWideViewPort();
 
     /**
      * Sets whether the WebView whether supports multiple windows. If set to
@@ -702,9 +629,7 @@
      *
      * @param support whether to suport multiple windows
      */
-    public synchronized void setSupportMultipleWindows(boolean support) {
-        throw new MustOverrideException();
-    }
+    public abstract void setSupportMultipleWindows(boolean support);
 
     /**
      * Gets whether the WebView supports multiple windows.
@@ -712,9 +637,7 @@
      * @return true if the WebView supports multiple windows
      * @see #setSupportMultipleWindows
      */
-    public synchronized boolean supportMultipleWindows() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean supportMultipleWindows();
 
     /**
      * Sets the underlying layout algorithm. This will cause a relayout of the
@@ -722,9 +645,7 @@
      *
      * @param l the layout algorithm to use, as a {@link LayoutAlgorithm} value
      */
-    public synchronized void setLayoutAlgorithm(LayoutAlgorithm l) {
-        throw new MustOverrideException();
-    }
+    public abstract void setLayoutAlgorithm(LayoutAlgorithm l);
 
     /**
      * Gets the current layout algorithm.
@@ -732,18 +653,14 @@
      * @return the layout algorithm in use, as a {@link LayoutAlgorithm} value
      * @see #setLayoutAlgorithm
      */
-    public synchronized LayoutAlgorithm getLayoutAlgorithm() {
-        throw new MustOverrideException();
-    }
+    public abstract LayoutAlgorithm getLayoutAlgorithm();
 
     /**
      * Sets the standard font family name. The default is "sans-serif".
      *
      * @param font a font family name
      */
-    public synchronized void setStandardFontFamily(String font) {
-        throw new MustOverrideException();
-    }
+    public abstract void setStandardFontFamily(String font);
 
     /**
      * Gets the standard font family name.
@@ -751,18 +668,14 @@
      * @return the standard font family name as a string
      * @see #setStandardFontFamily
      */
-    public synchronized String getStandardFontFamily() {
-        throw new MustOverrideException();
-    }
+    public abstract String getStandardFontFamily();
 
     /**
      * Sets the fixed font family name. The default is "monospace".
      *
      * @param font a font family name
      */
-    public synchronized void setFixedFontFamily(String font) {
-        throw new MustOverrideException();
-    }
+    public abstract void setFixedFontFamily(String font);
 
     /**
      * Gets the fixed font family name.
@@ -770,18 +683,14 @@
      * @return the fixed font family name as a string
      * @see #setFixedFontFamily
      */
-    public synchronized String getFixedFontFamily() {
-        throw new MustOverrideException();
-    }
+    public abstract String getFixedFontFamily();
 
     /**
      * Sets the sans-serif font family name. The default is "sans-serif".
      *
      * @param font a font family name
      */
-    public synchronized void setSansSerifFontFamily(String font) {
-        throw new MustOverrideException();
-    }
+    public abstract void setSansSerifFontFamily(String font);
 
     /**
      * Gets the sans-serif font family name.
@@ -789,18 +698,14 @@
      * @return the sans-serif font family name as a string
      * @see #setSansSerifFontFamily
      */
-    public synchronized String getSansSerifFontFamily() {
-        throw new MustOverrideException();
-    }
+    public abstract String getSansSerifFontFamily();
 
     /**
      * Sets the serif font family name. The default is "sans-serif".
      *
      * @param font a font family name
      */
-    public synchronized void setSerifFontFamily(String font) {
-        throw new MustOverrideException();
-    }
+    public abstract void setSerifFontFamily(String font);
 
     /**
      * Gets the serif font family name. The default is "serif".
@@ -808,18 +713,14 @@
      * @return the serif font family name as a string
      * @see #setSerifFontFamily
      */
-    public synchronized String getSerifFontFamily() {
-        throw new MustOverrideException();
-    }
+    public abstract String getSerifFontFamily();
 
     /**
      * Sets the cursive font family name. The default is "cursive".
      *
      * @param font a font family name
      */
-    public synchronized void setCursiveFontFamily(String font) {
-        throw new MustOverrideException();
-    }
+    public abstract void setCursiveFontFamily(String font);
 
     /**
      * Gets the cursive font family name.
@@ -827,18 +728,14 @@
      * @return the cursive font family name as a string
      * @see #setCursiveFontFamily
      */
-    public synchronized String getCursiveFontFamily() {
-        throw new MustOverrideException();
-    }
+    public abstract String getCursiveFontFamily();
 
     /**
      * Sets the fantasy font family name. The default is "fantasy".
      *
      * @param font a font family name
      */
-    public synchronized void setFantasyFontFamily(String font) {
-        throw new MustOverrideException();
-    }
+    public abstract void setFantasyFontFamily(String font);
 
     /**
      * Gets the fantasy font family name.
@@ -846,9 +743,7 @@
      * @return the fantasy font family name as a string
      * @see #setFantasyFontFamily
      */
-    public synchronized String getFantasyFontFamily() {
-        throw new MustOverrideException();
-    }
+    public abstract String getFantasyFontFamily();
 
     /**
      * Sets the minimum font size. The default is 8.
@@ -856,9 +751,7 @@
      * @param size a non-negative integer between 1 and 72. Any number outside
      *             the specified range will be pinned.
      */
-    public synchronized void setMinimumFontSize(int size) {
-        throw new MustOverrideException();
-    }
+    public abstract void setMinimumFontSize(int size);
 
     /**
      * Gets the minimum font size.
@@ -866,9 +759,7 @@
      * @return a non-negative integer between 1 and 72
      * @see #setMinimumFontSize
      */
-    public synchronized int getMinimumFontSize() {
-        throw new MustOverrideException();
-    }
+    public abstract int getMinimumFontSize();
 
     /**
      * Sets the minimum logical font size. The default is 8.
@@ -876,9 +767,7 @@
      * @param size a non-negative integer between 1 and 72. Any number outside
      *             the specified range will be pinned.
      */
-    public synchronized void setMinimumLogicalFontSize(int size) {
-        throw new MustOverrideException();
-    }
+    public abstract void setMinimumLogicalFontSize(int size);
 
     /**
      * Gets the minimum logical font size.
@@ -886,9 +775,7 @@
      * @return a non-negative integer between 1 and 72
      * @see #setMinimumLogicalFontSize
      */
-    public synchronized int getMinimumLogicalFontSize() {
-        throw new MustOverrideException();
-    }
+    public abstract int getMinimumLogicalFontSize();
 
     /**
      * Sets the default font size. The default is 16.
@@ -896,9 +783,7 @@
      * @param size a non-negative integer between 1 and 72. Any number outside
      *             the specified range will be pinned.
      */
-    public synchronized void setDefaultFontSize(int size) {
-        throw new MustOverrideException();
-    }
+    public abstract void setDefaultFontSize(int size);
 
     /**
      * Gets the default font size.
@@ -906,9 +791,7 @@
      * @return a non-negative integer between 1 and 72
      * @see #setDefaultFontSize
      */
-    public synchronized int getDefaultFontSize() {
-        throw new MustOverrideException();
-    }
+    public abstract int getDefaultFontSize();
 
     /**
      * Sets the default fixed font size. The default is 16.
@@ -916,9 +799,7 @@
      * @param size a non-negative integer between 1 and 72. Any number outside
      *             the specified range will be pinned.
      */
-    public synchronized void setDefaultFixedFontSize(int size) {
-        throw new MustOverrideException();
-    }
+    public abstract void setDefaultFixedFontSize(int size);
 
     /**
      * Gets the default fixed font size.
@@ -926,9 +807,7 @@
      * @return a non-negative integer between 1 and 72
      * @see #setDefaultFixedFontSize
      */
-    public synchronized int getDefaultFixedFontSize() {
-        throw new MustOverrideException();
-    }
+    public abstract int getDefaultFixedFontSize();
 
     /**
      * Sets whether the WebView should load image resources. Note that this method
@@ -941,9 +820,7 @@
      *
      * @param flag whether the WebView should load image resources
      */
-    public synchronized void setLoadsImagesAutomatically(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setLoadsImagesAutomatically(boolean flag);
 
     /**
      * Gets whether the WebView loads image resources. This includes
@@ -952,9 +829,7 @@
      * @return true if the WebView loads image resources
      * @see #setLoadsImagesAutomatically
      */
-    public synchronized boolean getLoadsImagesAutomatically() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getLoadsImagesAutomatically();
 
     /**
      * Sets whether the WebView should not load image resources from the
@@ -971,9 +846,7 @@
      *             network
      * @see #setBlockNetworkLoads
      */
-    public synchronized void setBlockNetworkImage(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setBlockNetworkImage(boolean flag);
 
     /**
      * Gets whether the WebView does not load image resources from the network.
@@ -981,9 +854,7 @@
      * @return true if the WebView does not load image resources from the network
      * @see #setBlockNetworkImage
      */
-    public synchronized boolean getBlockNetworkImage() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getBlockNetworkImage();
 
     /**
      * Sets whether the WebView should not load resources from the network.
@@ -1003,9 +874,7 @@
      *             network
      * @see android.webkit.WebView#reload
      */
-    public synchronized void setBlockNetworkLoads(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setBlockNetworkLoads(boolean flag);
 
     /**
      * Gets whether the WebView does not load any resources from the network.
@@ -1013,9 +882,7 @@
      * @return true if the WebView does not load any resources from the network
      * @see #setBlockNetworkLoads
      */
-    public synchronized boolean getBlockNetworkLoads() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getBlockNetworkLoads();
 
     /**
      * Tells the WebView to enable JavaScript execution.
@@ -1023,9 +890,7 @@
      *
      * @param flag true if the WebView should execute JavaScript
      */
-    public synchronized void setJavaScriptEnabled(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setJavaScriptEnabled(boolean flag);
 
     /**
      * Sets whether JavaScript running in the context of a file scheme URL
@@ -1076,10 +941,9 @@
      *             {@link #setPluginState}
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR2}
      */
+    @SystemApi
     @Deprecated
-    public synchronized void setPluginsEnabled(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setPluginsEnabled(boolean flag);
 
     /**
      * Tells the WebView to enable, disable, or have plugins on demand. On
@@ -1092,9 +956,7 @@
      * @deprecated Plugins will not be supported in future, and should not be used.
      */
     @Deprecated
-    public synchronized void setPluginState(PluginState state) {
-        throw new MustOverrideException();
-    }
+    public abstract void setPluginState(PluginState state);
 
     /**
      * Sets a custom path to plugins used by the WebView. This method is
@@ -1106,7 +968,7 @@
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR2}
      */
     @Deprecated
-    public synchronized void setPluginsPath(String pluginsPath) {
+    public void setPluginsPath(String pluginsPath) {
         // Specified to do nothing, so no need for derived classes to override.
     }
 
@@ -1125,9 +987,7 @@
     // Note that the WebCore Database Tracker only allows the path to be set
     // once.
     @Deprecated
-    public synchronized void setDatabasePath(String databasePath) {
-        throw new MustOverrideException();
-    }
+    public abstract void setDatabasePath(String databasePath);
 
     /**
      * Sets the path where the Geolocation databases should be saved. In order
@@ -1138,9 +998,7 @@
      *                     saved.
      */
     // This will update WebCore when the Sync runs in the C++ side.
-    public synchronized void setGeolocationDatabasePath(String databasePath) {
-        throw new MustOverrideException();
-    }
+    public abstract void setGeolocationDatabasePath(String databasePath);
 
     /**
      * Sets whether the Application Caches API should be enabled. The default
@@ -1150,9 +1008,7 @@
      *
      * @param flag true if the WebView should enable Application Caches
      */
-    public synchronized void setAppCacheEnabled(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setAppCacheEnabled(boolean flag);
 
     /**
      * Sets the path to the Application Caches files. In order for the
@@ -1164,9 +1020,7 @@
      *                     Application Caches files.
      * @see #setAppCacheEnabled
      */
-    public synchronized void setAppCachePath(String appCachePath) {
-        throw new MustOverrideException();
-    }
+    public abstract void setAppCachePath(String appCachePath);
 
     /**
      * Sets the maximum size for the Application Cache content. The passed size
@@ -1180,9 +1034,7 @@
      * @deprecated In future quota will be managed automatically.
      */
     @Deprecated
-    public synchronized void setAppCacheMaxSize(long appCacheMaxSize) {
-        throw new MustOverrideException();
-    }
+    public abstract void setAppCacheMaxSize(long appCacheMaxSize);
 
     /**
      * Sets whether the database storage API is enabled. The default value is
@@ -1196,18 +1048,14 @@
      *
      * @param flag true if the WebView should use the database storage API
      */
-    public synchronized void setDatabaseEnabled(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setDatabaseEnabled(boolean flag);
 
     /**
      * Sets whether the DOM storage API is enabled. The default value is false.
      *
      * @param flag true if the WebView should use the DOM storage API
      */
-    public synchronized void setDomStorageEnabled(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setDomStorageEnabled(boolean flag);
 
     /**
      * Gets whether the DOM Storage APIs are enabled.
@@ -1215,9 +1063,8 @@
      * @return true if the DOM Storage APIs are enabled
      * @see #setDomStorageEnabled
      */
-    public synchronized boolean getDomStorageEnabled() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getDomStorageEnabled();
+
     /**
      * Gets the path to where database storage API databases are saved.
      *
@@ -1226,9 +1073,7 @@
      * @deprecated Database paths are managed by the implementation this method is obsolete.
      */
     @Deprecated
-    public synchronized String getDatabasePath() {
-        throw new MustOverrideException();
-    }
+    public abstract String getDatabasePath();
 
     /**
      * Gets whether the database storage API is enabled.
@@ -1236,9 +1081,7 @@
      * @return true if the database storage API is enabled
      * @see #setDatabaseEnabled
      */
-    public synchronized boolean getDatabaseEnabled() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getDatabaseEnabled();
 
     /**
      * Sets whether Geolocation is enabled. The default is true.
@@ -1260,9 +1103,7 @@
      *
      * @param flag whether Geolocation should be enabled
      */
-    public synchronized void setGeolocationEnabled(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setGeolocationEnabled(boolean flag);
 
     /**
      * Gets whether JavaScript is enabled.
@@ -1270,9 +1111,7 @@
      * @return true if JavaScript is enabled
      * @see #setJavaScriptEnabled
      */
-    public synchronized boolean getJavaScriptEnabled() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getJavaScriptEnabled();
 
     /**
      * Gets whether JavaScript running in the context of a file scheme URL can
@@ -1303,10 +1142,9 @@
      * @deprecated This method has been replaced by {@link #getPluginState}
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR2}
      */
+    @SystemApi
     @Deprecated
-    public synchronized boolean getPluginsEnabled() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getPluginsEnabled();
 
     /**
      * Gets the current state regarding whether plugins are enabled.
@@ -1316,9 +1154,7 @@
      * @deprecated Plugins will not be supported in future, and should not be used.
      */
     @Deprecated
-    public synchronized PluginState getPluginState() {
-        throw new MustOverrideException();
-    }
+    public abstract PluginState getPluginState();
 
     /**
      * Gets the directory that contains the plugin libraries. This method is
@@ -1330,7 +1166,7 @@
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR2}
      */
     @Deprecated
-    public synchronized String getPluginsPath() {
+    public String getPluginsPath() {
         // Unconditionally returns empty string, so no need for derived classes to override.
         return "";
     }
@@ -1341,9 +1177,7 @@
      *
      * @param flag true if JavaScript can open windows automatically
      */
-    public synchronized void setJavaScriptCanOpenWindowsAutomatically(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setJavaScriptCanOpenWindowsAutomatically(boolean flag);
 
     /**
      * Gets whether JavaScript can open windows automatically.
@@ -1352,9 +1186,7 @@
      *         window.open()
      * @see #setJavaScriptCanOpenWindowsAutomatically
      */
-    public synchronized boolean getJavaScriptCanOpenWindowsAutomatically() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean getJavaScriptCanOpenWindowsAutomatically();
 
     /**
      * Sets the default text encoding name to use when decoding html pages.
@@ -1362,9 +1194,7 @@
      *
      * @param encoding the text encoding name
      */
-    public synchronized void setDefaultTextEncodingName(String encoding) {
-        throw new MustOverrideException();
-    }
+    public abstract void setDefaultTextEncodingName(String encoding);
 
     /**
      * Gets the default text encoding name.
@@ -1372,17 +1202,13 @@
      * @return the default text encoding name as a string
      * @see #setDefaultTextEncodingName
      */
-    public synchronized String getDefaultTextEncodingName() {
-        throw new MustOverrideException();
-    }
+    public abstract String getDefaultTextEncodingName();
 
     /**
      * Sets the WebView's user-agent string. If the string is null or empty,
      * the system default value will be used.
      */
-    public synchronized void setUserAgentString(String ua) {
-        throw new MustOverrideException();
-    }
+    public abstract void setUserAgentString(String ua);
 
     /**
      * Gets the WebView's user-agent string.
@@ -1390,9 +1216,7 @@
      * @return the WebView's user-agent string
      * @see #setUserAgentString
      */
-    public synchronized String getUserAgentString() {
-        throw new MustOverrideException();
-    }
+    public abstract String getUserAgentString();
 
     /**
      * Returns the default User-Agent used by a WebView.
@@ -1412,9 +1236,7 @@
      *
      * @param flag whether the WebView needs to set a node
      */
-    public void setNeedInitialFocus(boolean flag) {
-        throw new MustOverrideException();
-    }
+    public abstract void setNeedInitialFocus(boolean flag);
 
     /**
      * Sets the priority of the Render thread. Unlike the other settings, this
@@ -1426,9 +1248,7 @@
      *             not be supported in future versions.
      */
     @Deprecated
-    public synchronized void setRenderPriority(RenderPriority priority) {
-        throw new MustOverrideException();
-    }
+    public abstract void setRenderPriority(RenderPriority priority);
 
     /**
      * Overrides the way the cache is used. The way the cache is used is based
@@ -1442,9 +1262,7 @@
      *
      * @param mode the mode to use
      */
-    public void setCacheMode(int mode) {
-        throw new MustOverrideException();
-    }
+    public abstract void setCacheMode(int mode);
 
     /**
      * Gets the current setting for overriding the cache mode.
@@ -1452,9 +1270,7 @@
      * @return the current setting for overriding the cache mode
      * @see #setCacheMode
      */
-    public int getCacheMode() {
-        throw new MustOverrideException();
-    }
+    public abstract int getCacheMode();
 
     /**
      * Configures the WebView's behavior when a secure origin attempts to load a resource from an
diff --git a/core/java/android/webkit/WebStorage.java b/core/java/android/webkit/WebStorage.java
index 3bfe9cf..947d0cb 100644
--- a/core/java/android/webkit/WebStorage.java
+++ b/core/java/android/webkit/WebStorage.java
@@ -16,6 +16,8 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
+
 import java.util.Map;
 
 /**
@@ -65,23 +67,13 @@
         private long mUsage = 0;
 
         /** @hide */
+        @SystemApi
         protected Origin(String origin, long quota, long usage) {
             mOrigin = origin;
             mQuota = quota;
             mUsage = usage;
         }
 
-        /** @hide */
-        protected Origin(String origin, long quota) {
-            mOrigin = origin;
-            mQuota = quota;
-        }
-
-        /** @hide */
-        protected Origin(String origin) {
-            mOrigin = origin;
-        }
-
         /**
          * Gets the string representation of this origin.
          *
@@ -210,5 +202,6 @@
      * way to call createHandler() and createUIHandler(), so it would not work).
      * @hide
      */
+    @SystemApi
     public WebStorage() {}
 }
diff --git a/core/java/android/webkit/WebView.java b/core/java/android/webkit/WebView.java
index 40aee96..8d2c51f 100644
--- a/core/java/android/webkit/WebView.java
+++ b/core/java/android/webkit/WebView.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.annotation.Widget;
 import android.content.Context;
 import android.content.res.Configuration;
@@ -256,10 +257,12 @@
      * always stay as a hidden API.
      * @hide
      */
+    @SystemApi
     public static final String DATA_REDUCTION_PROXY_SETTING_CHANGED =
             "android.webkit.DATA_REDUCTION_PROXY_SETTING_CHANGED";
 
     private static final String LOGTAG = "WebView";
+    private static final boolean TRACE = false;
 
     // Throwing an exception for incorrect thread usage if the
     // build target is JB MR2 or newer. Defaults to false, and is
@@ -394,6 +397,7 @@
         /**
          * @hide Only for use by WebViewProvider implementations
          */
+        @SystemApi
         public HitTestResult() {
             mType = UNKNOWN_TYPE;
         }
@@ -401,6 +405,7 @@
         /**
          * @hide Only for use by WebViewProvider implementations
          */
+        @SystemApi
         public void setType(int type) {
             mType = type;
         }
@@ -408,6 +413,7 @@
         /**
          * @hide Only for use by WebViewProvider implementations
          */
+        @SystemApi
         public void setExtra(String extra) {
             mExtra = extra;
         }
@@ -542,7 +548,7 @@
         sEnforceThreadChecking = context.getApplicationInfo().targetSdkVersion >=
                 Build.VERSION_CODES.JELLY_BEAN_MR2;
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "WebView<init>");
+        if (TRACE) Log.d(LOGTAG, "WebView<init>");
 
         ensureProviderCreated();
         mProvider.init(javaScriptInterfaces, privateBrowsing);
@@ -557,7 +563,7 @@
      */
     public void setHorizontalScrollbarOverlay(boolean overlay) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "setHorizontalScrollbarOverlay=" + overlay);
+        if (TRACE) Log.d(LOGTAG, "setHorizontalScrollbarOverlay=" + overlay);
         mProvider.setHorizontalScrollbarOverlay(overlay);
     }
 
@@ -568,7 +574,7 @@
      */
     public void setVerticalScrollbarOverlay(boolean overlay) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "setVerticalScrollbarOverlay=" + overlay);
+        if (TRACE) Log.d(LOGTAG, "setVerticalScrollbarOverlay=" + overlay);
         mProvider.setVerticalScrollbarOverlay(overlay);
     }
 
@@ -623,7 +629,7 @@
     @Deprecated
     public void setCertificate(SslCertificate certificate) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "setCertificate=" + certificate);
+        if (TRACE) Log.d(LOGTAG, "setCertificate=" + certificate);
         mProvider.setCertificate(certificate);
     }
 
@@ -647,7 +653,7 @@
     @Deprecated
     public void savePassword(String host, String username, String password) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "savePassword=" + host);
+        if (TRACE) Log.d(LOGTAG, "savePassword=" + host);
         mProvider.savePassword(host, username, password);
     }
 
@@ -667,7 +673,7 @@
     public void setHttpAuthUsernamePassword(String host, String realm,
             String username, String password) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "setHttpAuthUsernamePassword=" + host);
+        if (TRACE) Log.d(LOGTAG, "setHttpAuthUsernamePassword=" + host);
         mProvider.setHttpAuthUsernamePassword(host, realm, username, password);
     }
 
@@ -697,7 +703,7 @@
      */
     public void destroy() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "destroy");
+        if (TRACE) Log.d(LOGTAG, "destroy");
         mProvider.destroy();
     }
 
@@ -743,7 +749,7 @@
      */
     public void setNetworkAvailable(boolean networkUp) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "setNetworkAvailable=" + networkUp);
+        if (TRACE) Log.d(LOGTAG, "setNetworkAvailable=" + networkUp);
         mProvider.setNetworkAvailable(networkUp);
     }
 
@@ -760,7 +766,7 @@
      */
     public WebBackForwardList saveState(Bundle outState) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "saveState");
+        if (TRACE) Log.d(LOGTAG, "saveState");
         return mProvider.saveState(outState);
     }
 
@@ -777,7 +783,7 @@
     @Deprecated
     public boolean savePicture(Bundle b, final File dest) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "savePicture=" + dest.getName());
+        if (TRACE) Log.d(LOGTAG, "savePicture=" + dest.getName());
         return mProvider.savePicture(b, dest);
     }
 
@@ -795,7 +801,7 @@
     @Deprecated
     public boolean restorePicture(Bundle b, File src) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "restorePicture=" + src.getName());
+        if (TRACE) Log.d(LOGTAG, "restorePicture=" + src.getName());
         return mProvider.restorePicture(b, src);
     }
 
@@ -813,7 +819,7 @@
      */
     public WebBackForwardList restoreState(Bundle inState) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "restoreState");
+        if (TRACE) Log.d(LOGTAG, "restoreState");
         return mProvider.restoreState(inState);
     }
 
@@ -830,7 +836,7 @@
      */
     public void loadUrl(String url, Map<String, String> additionalHttpHeaders) {
         checkThread();
-        if (DebugFlags.TRACE_API) {
+        if (TRACE) {
             StringBuilder headers = new StringBuilder();
             if (additionalHttpHeaders != null) {
                 for (Map.Entry<String, String> entry : additionalHttpHeaders.entrySet()) {
@@ -849,7 +855,7 @@
      */
     public void loadUrl(String url) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "loadUrl=" + url);
+        if (TRACE) Log.d(LOGTAG, "loadUrl=" + url);
         mProvider.loadUrl(url);
     }
 
@@ -864,7 +870,7 @@
      */
     public void postUrl(String url, byte[] postData) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "postUrl=" + url);
+        if (TRACE) Log.d(LOGTAG, "postUrl=" + url);
         if (URLUtil.isNetworkUrl(url)) {
             mProvider.postUrl(url, postData);
         } else {
@@ -903,7 +909,7 @@
      */
     public void loadData(String data, String mimeType, String encoding) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "loadData");
+        if (TRACE) Log.d(LOGTAG, "loadData");
         mProvider.loadData(data, mimeType, encoding);
     }
 
@@ -936,7 +942,7 @@
     public void loadDataWithBaseURL(String baseUrl, String data,
             String mimeType, String encoding, String historyUrl) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "loadDataWithBaseURL=" + baseUrl);
+        if (TRACE) Log.d(LOGTAG, "loadDataWithBaseURL=" + baseUrl);
         mProvider.loadDataWithBaseURL(baseUrl, data, mimeType, encoding, historyUrl);
     }
 
@@ -953,7 +959,7 @@
      */
     public void evaluateJavascript(String script, ValueCallback<String> resultCallback) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "evaluateJavascript=" + script);
+        if (TRACE) Log.d(LOGTAG, "evaluateJavascript=" + script);
         mProvider.evaluateJavaScript(script, resultCallback);
     }
 
@@ -964,7 +970,7 @@
      */
     public void saveWebArchive(String filename) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "saveWebArchive=" + filename);
+        if (TRACE) Log.d(LOGTAG, "saveWebArchive=" + filename);
         mProvider.saveWebArchive(filename);
     }
 
@@ -982,7 +988,7 @@
      */
     public void saveWebArchive(String basename, boolean autoname, ValueCallback<String> callback) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "saveWebArchive(auto)=" + basename);
+        if (TRACE) Log.d(LOGTAG, "saveWebArchive(auto)=" + basename);
         mProvider.saveWebArchive(basename, autoname, callback);
     }
 
@@ -991,7 +997,7 @@
      */
     public void stopLoading() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "stopLoading");
+        if (TRACE) Log.d(LOGTAG, "stopLoading");
         mProvider.stopLoading();
     }
 
@@ -1000,7 +1006,7 @@
      */
     public void reload() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "reload");
+        if (TRACE) Log.d(LOGTAG, "reload");
         mProvider.reload();
     }
 
@@ -1019,7 +1025,7 @@
      */
     public void goBack() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "goBack");
+        if (TRACE) Log.d(LOGTAG, "goBack");
         mProvider.goBack();
     }
 
@@ -1038,7 +1044,7 @@
      */
     public void goForward() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "goForward");
+        if (TRACE) Log.d(LOGTAG, "goForward");
         mProvider.goForward();
     }
 
@@ -1064,7 +1070,7 @@
      */
     public void goBackOrForward(int steps) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "goBackOrForwad=" + steps);
+        if (TRACE) Log.d(LOGTAG, "goBackOrForwad=" + steps);
         mProvider.goBackOrForward(steps);
     }
 
@@ -1084,7 +1090,7 @@
      */
     public boolean pageUp(boolean top) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "pageUp");
+        if (TRACE) Log.d(LOGTAG, "pageUp");
         return mProvider.pageUp(top);
     }
 
@@ -1096,7 +1102,7 @@
      */
     public boolean pageDown(boolean bottom) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "pageDown");
+        if (TRACE) Log.d(LOGTAG, "pageDown");
         return mProvider.pageDown(bottom);
     }
 
@@ -1109,7 +1115,7 @@
     @Deprecated
     public void clearView() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "clearView");
+        if (TRACE) Log.d(LOGTAG, "clearView");
         mProvider.clearView();
     }
 
@@ -1140,7 +1146,7 @@
     @Deprecated
     public Picture capturePicture() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "capturePicture");
+        if (TRACE) Log.d(LOGTAG, "capturePicture");
         return mProvider.capturePicture();
     }
 
@@ -1151,7 +1157,7 @@
     @Deprecated
     public PrintDocumentAdapter createPrintDocumentAdapter() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "createPrintDocumentAdapter");
+        if (TRACE) Log.d(LOGTAG, "createPrintDocumentAdapter");
         return mProvider.createPrintDocumentAdapter("default");
     }
 
@@ -1170,7 +1176,7 @@
      */
     public PrintDocumentAdapter createPrintDocumentAdapter(String documentName) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "createPrintDocumentAdapter");
+        if (TRACE) Log.d(LOGTAG, "createPrintDocumentAdapter");
         return mProvider.createPrintDocumentAdapter(documentName);
     }
 
@@ -1210,7 +1216,7 @@
      */
     public void setInitialScale(int scaleInPercent) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "setInitialScale=" + scaleInPercent);
+        if (TRACE) Log.d(LOGTAG, "setInitialScale=" + scaleInPercent);
         mProvider.setInitialScale(scaleInPercent);
     }
 
@@ -1221,7 +1227,7 @@
      */
     public void invokeZoomPicker() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "invokeZoomPicker");
+        if (TRACE) Log.d(LOGTAG, "invokeZoomPicker");
         mProvider.invokeZoomPicker();
     }
 
@@ -1245,7 +1251,7 @@
      */
     public HitTestResult getHitTestResult() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "getHitTestResult");
+        if (TRACE) Log.d(LOGTAG, "getHitTestResult");
         return mProvider.getHitTestResult();
     }
 
@@ -1264,7 +1270,7 @@
      */
     public void requestFocusNodeHref(Message hrefMsg) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "requestFocusNodeHref");
+        if (TRACE) Log.d(LOGTAG, "requestFocusNodeHref");
         mProvider.requestFocusNodeHref(hrefMsg);
     }
 
@@ -1277,7 +1283,7 @@
      */
     public void requestImageRef(Message msg) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "requestImageRef");
+        if (TRACE) Log.d(LOGTAG, "requestImageRef");
         mProvider.requestImageRef(msg);
     }
 
@@ -1382,7 +1388,7 @@
      */
     public void pauseTimers() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "pauseTimers");
+        if (TRACE) Log.d(LOGTAG, "pauseTimers");
         mProvider.pauseTimers();
     }
 
@@ -1392,7 +1398,7 @@
      */
     public void resumeTimers() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "resumeTimers");
+        if (TRACE) Log.d(LOGTAG, "resumeTimers");
         mProvider.resumeTimers();
     }
 
@@ -1405,7 +1411,7 @@
      */
     public void onPause() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "onPause");
+        if (TRACE) Log.d(LOGTAG, "onPause");
         mProvider.onPause();
     }
 
@@ -1414,7 +1420,7 @@
      */
     public void onResume() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "onResume");
+        if (TRACE) Log.d(LOGTAG, "onResume");
         mProvider.onResume();
     }
 
@@ -1437,7 +1443,7 @@
     @Deprecated
     public void freeMemory() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "freeMemory");
+        if (TRACE) Log.d(LOGTAG, "freeMemory");
         mProvider.freeMemory();
     }
 
@@ -1449,7 +1455,7 @@
      */
     public void clearCache(boolean includeDiskFiles) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "clearCache");
+        if (TRACE) Log.d(LOGTAG, "clearCache");
         mProvider.clearCache(includeDiskFiles);
     }
 
@@ -1461,7 +1467,7 @@
      */
     public void clearFormData() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "clearFormData");
+        if (TRACE) Log.d(LOGTAG, "clearFormData");
         mProvider.clearFormData();
     }
 
@@ -1470,7 +1476,7 @@
      */
     public void clearHistory() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "clearHistory");
+        if (TRACE) Log.d(LOGTAG, "clearHistory");
         mProvider.clearHistory();
     }
 
@@ -1480,7 +1486,7 @@
      */
     public void clearSslPreferences() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "clearSslPreferences");
+        if (TRACE) Log.d(LOGTAG, "clearSslPreferences");
         mProvider.clearSslPreferences();
     }
 
@@ -1496,7 +1502,7 @@
      *                   callback. The runnable will be called in UI thread.
      */
     public static void clearClientCertPreferences(Runnable onCleared) {
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "clearClientCertPreferences");
+        if (TRACE) Log.d(LOGTAG, "clearClientCertPreferences");
         getFactory().getStatics().clearClientCertPreferences(onCleared);
     }
 
@@ -1538,7 +1544,7 @@
      */
     public void findNext(boolean forward) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "findNext");
+        if (TRACE) Log.d(LOGTAG, "findNext");
         mProvider.findNext(forward);
     }
 
@@ -1554,7 +1560,7 @@
     @Deprecated
     public int findAll(String find) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "findAll");
+        if (TRACE) Log.d(LOGTAG, "findAll");
         StrictMode.noteSlowCall("findAll blocks UI: prefer findAllAsync");
         return mProvider.findAll(find);
     }
@@ -1569,7 +1575,7 @@
      */
     public void findAllAsync(String find) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "findAllAsync");
+        if (TRACE) Log.d(LOGTAG, "findAllAsync");
         mProvider.findAllAsync(find);
     }
 
@@ -1590,7 +1596,7 @@
     @Deprecated
     public boolean showFindDialog(String text, boolean showIme) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "showFindDialog");
+        if (TRACE) Log.d(LOGTAG, "showFindDialog");
         return mProvider.showFindDialog(text, showIme);
     }
 
@@ -1646,7 +1652,7 @@
      */
     public void clearMatches() {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "clearMatches");
+        if (TRACE) Log.d(LOGTAG, "clearMatches");
         mProvider.clearMatches();
     }
 
@@ -1707,7 +1713,7 @@
     @Deprecated
     public void setPictureListener(PictureListener listener) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "setPictureListener=" + listener);
+        if (TRACE) Log.d(LOGTAG, "setPictureListener=" + listener);
         mProvider.setPictureListener(listener);
     }
 
@@ -1764,7 +1770,7 @@
      */
     public void addJavascriptInterface(Object object, String name) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "addJavascriptInterface=" + name);
+        if (TRACE) Log.d(LOGTAG, "addJavascriptInterface=" + name);
         mProvider.addJavascriptInterface(object, name);
     }
 
@@ -1777,7 +1783,7 @@
      */
     public void removeJavascriptInterface(String name) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "removeJavascriptInterface=" + name);
+        if (TRACE) Log.d(LOGTAG, "removeJavascriptInterface=" + name);
         mProvider.removeJavascriptInterface(name);
     }
 
@@ -1881,7 +1887,7 @@
 
     public void flingScroll(int vx, int vy) {
         checkThread();
-        if (DebugFlags.TRACE_API) Log.d(LOGTAG, "flingScroll");
+        if (TRACE) Log.d(LOGTAG, "flingScroll");
         mProvider.flingScroll(vx, vy);
     }
 
@@ -2006,6 +2012,7 @@
      *
      * @hide WebViewProvider is not public API.
      */
+    @SystemApi
     public WebViewProvider getWebViewProvider() {
         return mProvider;
     }
@@ -2015,6 +2022,7 @@
      * and fields, and make super-class calls in this WebView instance.
      * @hide Only for use by WebViewProvider implementations
      */
+    @SystemApi
     public class PrivateAccess {
         // ---- Access to super-class methods ----
         public int super_getScrollBarStyle() {
diff --git a/core/java/android/webkit/WebViewDatabase.java b/core/java/android/webkit/WebViewDatabase.java
index 99e0ffb..bfea481 100644
--- a/core/java/android/webkit/WebViewDatabase.java
+++ b/core/java/android/webkit/WebViewDatabase.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.content.Context;
 
 /**
@@ -28,18 +29,12 @@
  *  <li>Data entered into text fields (e.g. for autocomplete suggestions)</li>
  * </ul>
  */
-public class WebViewDatabase {
+public abstract class WebViewDatabase {
     /**
      * @hide Since API level {@link android.os.Build.VERSION_CODES#JELLY_BEAN_MR1}
      */
     protected static final String LOGTAG = "webviewdatabase";
 
-    /**
-     * @hide Only for use by WebViewProvider implementations.
-     */
-    protected WebViewDatabase() {
-    }
-
     public static WebViewDatabase getInstance(Context context) {
         return WebViewFactory.getProvider().getWebViewDatabase(context);
     }
@@ -54,9 +49,7 @@
      * @deprecated Saving passwords in WebView will not be supported in future versions.
      */
     @Deprecated
-    public boolean hasUsernamePassword() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean hasUsernamePassword();
 
     /**
      * Clears any saved username/password pairs for web forms.
@@ -67,9 +60,7 @@
      * @deprecated Saving passwords in WebView will not be supported in future versions.
      */
     @Deprecated
-    public void clearUsernamePassword() {
-        throw new MustOverrideException();
-    }
+    public abstract void clearUsernamePassword();
 
     /**
      * Gets whether there are any saved credentials for HTTP authentication.
@@ -79,9 +70,7 @@
      * @see WebView#setHttpAuthUsernamePassword
      * @see #clearHttpAuthUsernamePassword
      */
-    public boolean hasHttpAuthUsernamePassword() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean hasHttpAuthUsernamePassword();
 
     /**
      * Clears any saved credentials for HTTP authentication.
@@ -90,9 +79,7 @@
      * @see WebView#setHttpAuthUsernamePassword
      * @see #hasHttpAuthUsernamePassword
      */
-    public void clearHttpAuthUsernamePassword() {
-        throw new MustOverrideException();
-    }
+    public abstract void clearHttpAuthUsernamePassword();
 
     /**
      * Gets whether there is any saved data for web forms.
@@ -100,16 +87,12 @@
      * @return whether there is any saved data for web forms
      * @see #clearFormData
      */
-    public boolean hasFormData() {
-        throw new MustOverrideException();
-    }
+    public abstract boolean hasFormData();
 
     /**
      * Clears any saved data for web forms.
      *
      * @see #hasFormData
      */
-    public void clearFormData() {
-        throw new MustOverrideException();
-    }
+    public abstract void clearFormData();
 }
diff --git a/core/java/android/webkit/WebViewDelegate.java b/core/java/android/webkit/WebViewDelegate.java
index c878b3d..3dcfda3 100644
--- a/core/java/android/webkit/WebViewDelegate.java
+++ b/core/java/android/webkit/WebViewDelegate.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.app.ActivityThread;
 import android.app.Application;
 import android.content.Context;
@@ -35,6 +36,7 @@
  *
  * @hide
  */
+@SystemApi
 public final class WebViewDelegate {
 
     /* package */ WebViewDelegate() { }
diff --git a/core/java/android/webkit/WebViewFactory.java b/core/java/android/webkit/WebViewFactory.java
index ca9f378..7b23d8f 100644
--- a/core/java/android/webkit/WebViewFactory.java
+++ b/core/java/android/webkit/WebViewFactory.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.app.ActivityManagerInternal;
 import android.app.Application;
 import android.app.AppGlobals;
@@ -46,6 +47,7 @@
  *
  * @hide
  */
+@SystemApi
 public final class WebViewFactory {
 
     private static final String CHROMIUM_WEBVIEW_FACTORY =
diff --git a/core/java/android/webkit/WebViewFactoryProvider.java b/core/java/android/webkit/WebViewFactoryProvider.java
index d37d217..9105394 100644
--- a/core/java/android/webkit/WebViewFactoryProvider.java
+++ b/core/java/android/webkit/WebViewFactoryProvider.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.content.Context;
 import android.content.Intent;
 import android.net.Uri;
@@ -26,6 +27,7 @@
  * implementation of this interface, and make it available to the WebView via mechanism TBD.
  * @hide
  */
+@SystemApi
 public interface WebViewFactoryProvider {
     /**
      * This Interface provides glue for implementing the backend of WebView static methods which
diff --git a/core/java/android/webkit/WebViewProvider.java b/core/java/android/webkit/WebViewProvider.java
index fe18138..2aee57b 100644
--- a/core/java/android/webkit/WebViewProvider.java
+++ b/core/java/android/webkit/WebViewProvider.java
@@ -16,6 +16,7 @@
 
 package android.webkit;
 
+import android.annotation.SystemApi;
 import android.content.res.Configuration;
 import android.graphics.Bitmap;
 import android.graphics.Canvas;
@@ -53,6 +54,7 @@
  *
  * @hide Not part of the public API; only required by system implementors.
  */
+@SystemApi
 public interface WebViewProvider {
     //-------------------------------------------------------------------------
     // Main interface for backend provider of the WebView class.