Introduce PrefRegistrySyncable, simplifying PrefServiceSyncable.

chrome/browser/prefs/incognito_mode_prefs.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_INCOGNITO_MODE_PREFS_H_
 #define CHROME_BROWSER_PREFS_INCOGNITO_MODE_PREFS_H_
 
 #include "base/basictypes.h"
 
 class CommandLine;
 class PrefService;
-class PrefServiceSyncable;
+class PrefRegistrySyncable;
 
 // Specifies Incognito mode availability preferences.
 class IncognitoModePrefs {
  public:
   // Possible values for Incognito mode availability. Please, do not change
   // the order of entries since numeric values are exposed to users.
   enum Availability {
     // Incognito mode enabled. Users may open pages in both Incognito mode and
     // normal mode (the default behaviour).
     ENABLED = 0,
     // Incognito mode disabled. Users may not open pages in Incognito mode.
     // Only normal mode is available for browsing.
     DISABLED,
     // Incognito mode forced. Users may open pages *ONLY* in Incognito mode.
     // Normal mode is not available for browsing.
     FORCED,
 
     AVAILABILITY_NUM_TYPES
   };
 
   // Register incognito related preferences.
-  static void RegisterUserPrefs(PrefServiceSyncable* prefs);
+  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
 
   // Returns kIncognitoModeAvailability preference value stored
   // in the given pref service.
   static Availability GetAvailability(const PrefService* prefs);
 
   // Sets kIncognitoModeAvailability preference to the specified availability
   // value.
   static void SetAvailability(PrefService* prefs,
                               const Availability availability);
 
   // Converts in_value into the corresponding Availability value. Returns true
   // if conversion is successful (in_value is valid). Otherwise, returns false
   // and *out_value is set to ENABLED.
   static bool IntToAvailability(int in_value, Availability* out_value);
 
   // Returns true if the browser should start in incognito mode.
   static bool ShouldLaunchIncognito(const CommandLine& command_line,
                                     const PrefService* prefs);
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(IncognitoModePrefs);
 };
 
 #endif  // CHROME_BROWSER_PREFS_INCOGNITO_MODE_PREFS_H_