Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/content_settings/cookie_settings.h

Index: chrome/browser/content_settings/cookie_settings.h
diff --git a/chrome/browser/content_settings/cookie_settings.h b/chrome/browser/content_settings/cookie_settings.h
index f76ce0d7590ab3b3f9c917accd85eb4b2d073eb5..5be1c4ca955510a5e8f06d4c2e4d50d9731a1025 100644
--- a/chrome/browser/content_settings/cookie_settings.h
+++ b/chrome/browser/content_settings/cookie_settings.h
@@ -21,7 +21,7 @@ class ContentSettingsPattern;
 class CookieSettingsWrapper;
 class GURL;
 class PrefService;
-class PrefServiceSyncable;
+class PrefRegistrySyncable;
 class Profile;
 
 // A frontend to the cookie settings of |HostContentSettingsMap|. Handles
@@ -102,7 +102,7 @@ class CookieSettings
       bool setting_cookie,
       content_settings::SettingSource* source) const;
 
-  static void RegisterUserPrefs(PrefServiceSyncable* prefs);
+  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
 
   class Factory : public RefcountedProfileKeyedServiceFactory {
    public:
@@ -120,7 +120,7 @@ class CookieSettings
     virtual ~Factory();
 
     // |ProfileKeyedBaseFactory| methods:
-    virtual void RegisterUserPrefs(PrefServiceSyncable* user_prefs) OVERRIDE;
+    virtual void RegisterUserPrefs(PrefRegistrySyncable* registry) OVERRIDE;
     virtual bool ServiceRedirectedInIncognito() const OVERRIDE;
     virtual scoped_refptr<RefcountedProfileKeyedService>
         BuildServiceInstanceFor(Profile* profile) const OVERRIDE;