Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/spellchecker/spellcheck_factory.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_SPELLCHECKER_SPELLCHECK_FACTORY_H_
 #define CHROME_BROWSER_SPELLCHECKER_SPELLCHECK_FACTORY_H_
 
 #include "base/basictypes.h"
 #include "base/memory/singleton.h"
 #include "chrome/browser/profiles/profile_keyed_service_factory.h"
 
+class PrefRegistrySyncable;
 class SpellcheckService;
 
 // Entry into the SpellCheck system.
 //
 // Internally, this owns all SpellcheckService objects.
 class SpellcheckServiceFactory : public ProfileKeyedServiceFactory {
  public:
   // Returns the spell check host. This may be NULL.
   static SpellcheckService* GetForProfile(Profile* profile);
 
   static SpellcheckServiceFactory* GetInstance();
 
  private:
   friend struct DefaultSingletonTraits<SpellcheckServiceFactory>;
 
   SpellcheckServiceFactory();
   virtual ~SpellcheckServiceFactory();
 
   // ProfileKeyedServiceFactory:
   virtual ProfileKeyedService* BuildServiceInstanceFor(
       Profile* profile) const OVERRIDE;
-  virtual void RegisterUserPrefs(PrefServiceSyncable* user_prefs) OVERRIDE;
+  virtual void RegisterUserPrefs(PrefRegistrySyncable* registry) OVERRIDE;
   virtual bool ServiceRedirectedInIncognito() const OVERRIDE;
   virtual bool ServiceIsNULLWhileTesting() const OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(SpellcheckServiceFactory);
 };
 
 #endif  // CHROME_BROWSER_SPELLCHECKER_SPELLCHECK_FACTORY_H_