Add preview for contrast

 Bug: 5135321
 Bug: 5118011
 Add a preview for the contrast accisibility settings.
 Rename FontSizePreference to the more generic SeekBarSummaryPreference
 as it has nothing to do with font size specifically.

Change-Id: Id516d63d62822cf026af3ce531ec33eb48ae667a
diff --git a/src/com/android/browser/BrowserSettings.java b/src/com/android/browser/BrowserSettings.java
index b3f7689..ad42146 100644
--- a/src/com/android/browser/BrowserSettings.java
+++ b/src/com/android/browser/BrowserSettings.java
@@ -250,10 +250,10 @@
             settings.setUserAgentString(USER_AGENTS[getUserAgent()]);
         }
 
-        settings.setProperty(PREF_INVERTED,
+        settings.setProperty(WebViewProperties.gfxInvertedScreen,
                 useInvertedRendering() ? "true" : "false");
 
-        settings.setProperty(PREF_INVERTED_CONTRAST,
+        settings.setProperty(WebViewProperties.gfxInvertedScreenContrast,
                 Float.toString(getInvertedContrast()));
     }
 
@@ -742,10 +742,6 @@
         return 1 + (mPrefs.getInt(PREF_INVERTED_CONTRAST, 0) / 10f);
     }
 
-    public void setInvertedContrast(int contrast) {
-        mPrefs.edit().putInt(PREF_INVERTED_CONTRAST, contrast).apply();
-    }
-
     // -----------------------------
     // getter/setters for privacy_security_preferences.xml
     // -----------------------------