components: Move PrefRegistrySyncable into user_prefs namespace.

chrome/browser/ui/webui/plugins_ui.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_UI_WEBUI_PLUGINS_UI_H_
 #define CHROME_BROWSER_UI_WEBUI_PLUGINS_UI_H_
 
 #include "content/public/browser/web_ui_controller.h"
 #include "ui/base/layout.h"
 
-class PrefRegistrySyncable;
-
 namespace base {
 class RefCountedMemory;
 }
 
+namespace user_prefs {
+class PrefRegistrySyncable;
+}
+
 class PluginsUI : public content::WebUIController {
  public:
   explicit PluginsUI(content::WebUI* web_ui);
 
   static base::RefCountedMemory* GetFaviconResourceBytes(
       ui::ScaleFactor scale_factor);
-  static void RegisterUserPrefs(PrefRegistrySyncable* registry);
+  static void RegisterUserPrefs(user_prefs::PrefRegistrySyncable* registry);
 
  private:
   DISALLOW_COPY_AND_ASSIGN(PluginsUI);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_PLUGINS_UI_H_