Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/prefs/pref_service_syncable_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_SYNCABLE_BUILDER_H_
 #define CHROME_BROWSER_PREFS_PREF_SERVICE_SYNCABLE_BUILDER_H_
 
 #include "chrome/browser/prefs/pref_service_builder.h"
 
 class CommandLine;
+class PrefRegistrySyncable;
 class PrefServiceSyncable;
 
 namespace policy {
 class PolicyService;
 }
 
 // A PrefServiceBuilder that also knows how to build a
 // PrefServiceSyncable, and may know about Chrome concepts such as
 // PolicyService.
 class PrefServiceSyncableBuilder : public PrefServiceBuilder {
  public:
   PrefServiceSyncableBuilder();
   virtual ~PrefServiceSyncableBuilder();
 
 #if defined(ENABLE_CONFIGURATION_POLICY)
   // Set up policy pref stores using the given policy service.
   PrefServiceSyncableBuilder& WithManagedPolicies(
       policy::PolicyService* service);
   PrefServiceSyncableBuilder& WithRecommendedPolicies(
       policy::PolicyService* service);
 #endif
 
   // Specifies to use an actual command-line backed command-line pref store.
   PrefServiceSyncableBuilder& WithCommandLine(CommandLine* command_line);
 
-  virtual PrefServiceSyncable* CreateSyncable();
+  virtual PrefServiceSyncable* CreateSyncable(PrefRegistrySyncable* registry);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PrefServiceSyncableBuilder);
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_SERVICE_SYNCABLE_BUILDER_H_