[Android] Migrate javascript settings to a content setting from a pref.

chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java

Index: chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java
diff --git a/chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java b/chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java
index c3005e17b81555db9ea8ccf8dd3c2f87c4c983e8..d2332b48a8c42ea4b7df49b9763cbf8e0f4729a5 100644
--- a/chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java
+++ b/chrome/android/java/src/org/chromium/chrome/browser/preferences/PrefServiceBridge.java
@@ -4,7 +4,11 @@
 
 package org.chromium.chrome.browser.preferences;
 
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.preference.PreferenceManager;
 import android.text.TextUtils;
+import android.util.Log;
 
 import org.chromium.base.CalledByNative;
 import org.chromium.base.ThreadUtils;
@@ -31,6 +35,9 @@ public final class PrefServiceBridge {
     public static final int SUPERVISED_USER_FILTERING_WARN = 1;
     public static final int SUPERVISED_USER_FILTERING_BLOCK = 2;
 
+    private static final String MIGRATION_PREF_KEY = "PrefMigrationVersion";
+    private static final int MIGRATION_CURRENT_VERSION = 1;
+
     private static String sProfilePath;
 
     // Object to notify when "clear browsing data" completes.
@@ -143,6 +150,25 @@ public final class PrefServiceBridge {
     }
 
     /**
+     * Migrates (synchronously) the preferences to the most recent version.
+     */
+    public void migratePreferences(Context context) {
+        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
+        int currentVersion = preferences.getInt(MIGRATION_PREF_KEY, 0);
+        if (currentVersion == MIGRATION_CURRENT_VERSION) return;
+        if (currentVersion > MIGRATION_CURRENT_VERSION) {
+            Log.e(LOG_TAG, "Saved preferences version is newer than supported.  Attempting to "
+                    + "run an older version of Chrome without clearing data is unsupported and "
+                    + "the results may be unpredictable.");
+        }
+
+        if (currentVersion <= 0) {
+            nativeMigrateJavascriptPreference();
+        }
+        preferences.edit().putInt(MIGRATION_PREF_KEY, MIGRATION_CURRENT_VERSION).commit();
+    }
+
+    /**
      * Returns the path to the user's profile directory via a callback. The callback may be
      * called synchronously or asynchronously.
      */
@@ -746,6 +772,7 @@ public final class PrefServiceBridge {
     private native void nativeResetTranslateDefaults();
     private native boolean nativeGetJavaScriptEnabled();
     private native void nativeSetJavaScriptEnabled(boolean enabled);
+    private native void nativeMigrateJavascriptPreference();
     private native void nativeClearBrowsingData(boolean history, boolean cache,
             boolean cookiesAndSiteData, boolean passwords, boolean formData);
     private native void nativeSetAllowCookiesEnabled(boolean allow);