Re-implement UserAgent in browser

- Remove calls to SWE's WebSetting API and use the newer implementation of
  the engine. The newer implementation tracks UserAgent per navigation
  entry.
- Allow to override the UserAgent using command line switches.
- Remove debug option to change UserAgent string.
- BrowserConfig class cleanup.

Change-Id: Ib1cc4763e0cbf0207793d1f4e6b1644a9dbb5c08
diff --git a/res/values/strings.xml b/res/values/strings.xml
index 190f690..61f4c36 100644
--- a/res/values/strings.xml
+++ b/res/values/strings.xml
@@ -587,23 +587,6 @@
     <!-- Do not tranlsate.  Development option -->
     <string name="pref_development_uastring" translatable="false">UAString</string>
     <!-- Do not tranlsate.  Development option -->
-    <string-array name="pref_development_ua_choices" translatable="false">
-        <item>Android</item>
-        <item>Desktop</item>
-        <item>iPhone</item>
-        <item>iPad</item>
-        <item>Froyo-N1</item>
-        <item>Honeycomb-Xoom</item>
-    </string-array>
-    <!-- Do not tranlsate.  Development option -->
-    <string-array name="pref_development_ua_values" translatable="false">
-        <item>0</item>
-        <item>1</item>
-        <item>2</item>
-        <item>3</item>
-        <item>4</item>
-        <item>5</item>
-    </string-array>
     <string name="pref_development_error_console" translatable="false">Show JavaScript Console</string>
     <!-- Do not translate. Development option to reset the prologin time [CHAR LIMIT=20] -->
     <string name="pref_development_reset_prelogin" translatable="false">Reset prelogin</string>
diff --git a/res/xml/debug_preferences.xml b/res/xml/debug_preferences.xml
index 8e169bd..3ab9b90 100644
--- a/res/xml/debug_preferences.xml
+++ b/res/xml/debug_preferences.xml
@@ -14,7 +14,7 @@
      limitations under the License.
 -->
 
-<PreferenceScreen 
+<PreferenceScreen
         xmlns:android="http://schemas.android.com/apk/res/android" >
 
     <CheckBoxPreference
@@ -28,13 +28,6 @@
         android:title="@string/pref_development_hardware_accel_skia"
         android:enabled="false" />
 
-    <ListPreference
-        android:key="user_agent"
-        android:title="@string/pref_development_uastring"
-        android:entries="@array/pref_development_ua_choices"
-        android:entryValues="@array/pref_development_ua_values"
-        android:defaultValue="0"/>
-
     <CheckBoxPreference
         android:key="enable_visual_indicator"
         android:defaultValue="false"