Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/prefs/pref_service_mock_builder.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_PREFS_PREF_SERVICE_MOCK_BUILDER_H_
 #define CHROME_BROWSER_PREFS_PREF_SERVICE_MOCK_BUILDER_H_
 
 #include "chrome/browser/prefs/pref_service_syncable_builder.h"
 
 class PrefService;
+class PrefRegistrySyncable;
 class PrefServiceSyncable;
 
 // A helper that allows convenient building of custom PrefServices in tests.
 class PrefServiceMockBuilder : public PrefServiceSyncableBuilder {
  public:
   PrefServiceMockBuilder();
   virtual ~PrefServiceMockBuilder();
 
   // Creates a PrefService for testing, invalidating the entire
   // builder configuration.
   virtual PrefService* Create(PrefRegistry* pref_registry) OVERRIDE;
-  virtual PrefServiceSyncable* CreateSyncable() OVERRIDE;
+  virtual PrefServiceSyncable* CreateSyncable(
+      PrefRegistrySyncable* pref_registry) OVERRIDE;
 
  private:
   virtual void ResetDefaultState() OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(PrefServiceMockBuilder);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_SERVICE_MOCK_BUILDER_H_