diff -r 000000000000 -r 6474c204b198 mobile/android/base/GeckoSharedPrefs.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mobile/android/base/GeckoSharedPrefs.java	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,275 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.gecko;
+
+import org.mozilla.gecko.mozglue.RobocopTarget;
+import org.mozilla.gecko.util.ThreadUtils;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.content.SharedPreferences.Editor;
+import android.os.Build;
+import android.os.StrictMode;
+import android.preference.PreferenceManager;
+import android.util.Log;
+
+import java.util.Arrays;
+import java.util.EnumSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+/**
+ * {@code GeckoSharedPrefs} provides scoped SharedPreferences instances.
+ * You should use this API instead of using Context.getSharedPreferences()
+ * directly. There are three methods to get scoped SharedPreferences instances:
+ *
+ * forApp()
+ *     Use it for app-wide, cross-profile pref keys.
+ * forProfile()
+ *     Use it to fetch and store keys for the current profile.
+ * forProfileName()
+ *     Use it to fetch and store keys from/for a specific profile.
+ *
+ * {@code GeckoSharedPrefs} has a notion of migrations. Migrations can used to
+ * migrate keys from one scope to another. You can trigger a new migration by
+ * incrementing PREFS_VERSION and updating migrateIfNecessary() accordingly.
+ *
+ * Migration history:
+ *     1: Move all PreferenceManager keys to app/profile scopes
+ */
+@RobocopTarget
+public final class GeckoSharedPrefs {
+    private static final String LOGTAG = "GeckoSharedPrefs";
+
+    // Increment it to trigger a new migration
+    public static final int PREFS_VERSION = 1;
+
+    // Name for app-scoped prefs
+    public static final String APP_PREFS_NAME = "GeckoApp";
+
+    // The prefs key that holds the current migration
+    private static final String PREFS_VERSION_KEY = "gecko_shared_prefs_migration";
+
+    // For disabling migration when getting a SharedPreferences instance
+    private static final EnumSet<Flags> disableMigrations = EnumSet.of(Flags.DISABLE_MIGRATIONS);
+
+    // Timeout for migration commits to be done (10 seconds)
+    private static final int MIGRATION_COMMIT_TIMEOUT_MSEC = 10000;
+
+    // The keys that have to be moved from ProfileManager's default
+    // shared prefs to the profile from version 0 to 1.
+    private static final String[] PROFILE_MIGRATIONS_0_TO_1 = {
+        "home_panels",
+        "home_locale"
+    };
+
+    // For optimizing the migration check in subsequent get() calls
+    private static volatile boolean migrationDone = false;
+
+    public enum Flags {
+        DISABLE_MIGRATIONS
+    }
+
+    // Used when fetching profile-scoped prefs.
+    private static final String PROFILE_PREFS_NAME_PREFIX = "GeckoProfile-";
+
+    public static SharedPreferences forApp(Context context) {
+        return forApp(context, EnumSet.noneOf(Flags.class));
+    }
+
+    /**
+     * Returns an app-scoped SharedPreferences instance. You can disable
+     * migrations by using the DISABLE_MIGRATIONS flag.
+     */
+    public static SharedPreferences forApp(Context context, EnumSet<Flags> flags) {
+        if (flags != null && !flags.contains(Flags.DISABLE_MIGRATIONS)) {
+            migrateIfNecessary(context);
+        }
+
+        return context.getSharedPreferences(APP_PREFS_NAME, 0);
+    }
+
+    public static SharedPreferences forProfile(Context context) {
+        return forProfile(context, EnumSet.noneOf(Flags.class));
+    }
+
+    /**
+     * Returns a SharedPreferences instance scoped to the current profile
+     * in the app. You can disable migrations by using the DISABLE_MIGRATIONS
+     * flag.
+     */
+    public static SharedPreferences forProfile(Context context, EnumSet<Flags> flags) {
+        String profileName = GeckoProfile.get(context).getName();
+        if (profileName == null) {
+            throw new IllegalStateException("Could not get current profile name");
+        }
+
+        return forProfileName(context, profileName, flags);
+    }
+
+    public static SharedPreferences forProfileName(Context context, String profileName) {
+        return forProfileName(context, profileName, EnumSet.noneOf(Flags.class));
+    }
+
+    /**
+     * Returns an SharedPreferences instance scoped to the given profile name.
+     * You can disable migrations by using the DISABLE_MIGRATION flag.
+     */
+    public static SharedPreferences forProfileName(Context context, String profileName,
+            EnumSet<Flags> flags) {
+        if (flags != null && !flags.contains(Flags.DISABLE_MIGRATIONS)) {
+            migrateIfNecessary(context);
+        }
+
+        final String prefsName = PROFILE_PREFS_NAME_PREFIX + profileName;
+        return context.getSharedPreferences(prefsName, 0);
+    }
+
+    /**
+     * Returns the current version of the prefs.
+     */
+    public static int getVersion(Context context) {
+        return forApp(context, disableMigrations).getInt(PREFS_VERSION_KEY, 0);
+    }
+
+    /**
+     * Resets migration flag. Should only be used in tests.
+     */
+    public static synchronized void reset() {
+        migrationDone = false;
+    }
+
+    /**
+     * Performs all prefs migrations in the background thread to avoid StrictMode
+     * exceptions from reading/writing in the UI thread. This method will block
+     * the current thread until the migration is finished.
+     */
+    private static synchronized void migrateIfNecessary(final Context context) {
+        if (migrationDone) {
+            return;
+        }
+
+        // We deliberatly perform the migration in the current thread (which
+        // is likely the UI thread) as this is actually cheaper than enforcing a
+        // context switch to another thread (see bug 940575).
+        if (Build.VERSION.SDK_INT < 9) {
+            performMigration(context);
+        } else {
+            // Avoid strict mode warnings.
+            final StrictMode.ThreadPolicy savedPolicy = StrictMode.allowThreadDiskReads();
+            StrictMode.allowThreadDiskWrites();
+
+            try {
+                performMigration(context);
+            } finally {
+                StrictMode.setThreadPolicy(savedPolicy);
+            }
+        }
+
+        migrationDone = true;
+    }
+
+    private static void performMigration(Context context) {
+        final SharedPreferences appPrefs = forApp(context, disableMigrations);
+
+        final int currentVersion = appPrefs.getInt(PREFS_VERSION_KEY, 0);
+        Log.d(LOGTAG, "Current version = " + currentVersion + ", prefs version = " + PREFS_VERSION);
+
+        if (currentVersion == PREFS_VERSION) {
+            return;
+        }
+
+        Log.d(LOGTAG, "Performing migration");
+
+        final Editor appEditor = appPrefs.edit();
+
+        // The migration always moves prefs to the default profile, not
+        // the current one. We might have to revisit this if we ever support
+        // multiple profiles.
+        final String defaultProfileName;
+        try {
+            defaultProfileName = GeckoProfile.getDefaultProfileName(context);
+        } catch (Exception e) {
+            throw new IllegalStateException("Failed to get default profile name for migration");
+        }
+
+        final Editor profileEditor = forProfileName(context, defaultProfileName, disableMigrations).edit();
+
+        List<String> profileKeys;
+        Editor pmEditor = null;
+
+        for (int v = currentVersion + 1; v <= PREFS_VERSION; v++) {
+            Log.d(LOGTAG, "Migrating to version = " + v);
+
+            switch (v) {
+                case 1:
+                    profileKeys = Arrays.asList(PROFILE_MIGRATIONS_0_TO_1);
+                    pmEditor = migrateFromPreferenceManager(context, appEditor, profileEditor, profileKeys);
+                    break;
+            }
+        }
+
+        // Update prefs version accordingly.
+        appEditor.putInt(PREFS_VERSION_KEY, PREFS_VERSION);
+
+        appEditor.commit();
+        profileEditor.commit();
+        if (pmEditor != null) {
+            pmEditor.commit();
+        }
+
+        Log.d(LOGTAG, "All keys have been migrated");
+    }
+
+    /**
+     * Moves all preferences stored in PreferenceManager's default prefs
+     * to either app or profile scopes. The profile-scoped keys are defined
+     * in given profileKeys list, all other keys are moved to the app scope.
+     */
+    public static Editor migrateFromPreferenceManager(Context context, Editor appEditor,
+            Editor profileEditor, List<String> profileKeys) {
+        Log.d(LOGTAG, "Migrating from PreferenceManager");
+
+        final SharedPreferences pmPrefs =
+                PreferenceManager.getDefaultSharedPreferences(context);
+
+        for (Map.Entry<String, ?> entry : pmPrefs.getAll().entrySet()) {
+            final String key = entry.getKey();
+
+            final Editor to;
+            if (profileKeys.contains(key)) {
+                to = profileEditor;
+            } else {
+                to = appEditor;
+            }
+
+            putEntry(to, key, entry.getValue());
+        }
+
+        // Clear PreferenceManager's prefs once we're done
+        // and return the Editor to be committed.
+        return pmPrefs.edit().clear();
+    }
+
+    @SuppressWarnings("unchecked")
+    private static void putEntry(Editor to, String key, Object value) {
+        Log.d(LOGTAG, "Migrating key = " + key + " with value = " + value);
+
+        if (value instanceof String) {
+            to.putString(key, (String) value);
+        } else if (value instanceof Boolean) {
+            to.putBoolean(key, (Boolean) value);
+        } else if (value instanceof Long) {
+            to.putLong(key, (Long) value);
+        } else if (value instanceof Float) {
+            to.putFloat(key, (Float) value);
+        } else if (value instanceof Integer) {
+            to.putInt(key, (Integer) value);
+        } else {
+            throw new IllegalStateException("Unrecognized value type for key: " + key);
+        }
+    }
+}
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