Remove content::NotificationObserver dependency from most Prefs code.

chrome/browser/background/background_mode_manager.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_BACKGROUND_BACKGROUND_MODE_MANAGER_H_
 #define CHROME_BROWSER_BACKGROUND_BACKGROUND_MODE_MANAGER_H_
 
 #include <map>
 
 #include "base/gtest_prod_util.h"
 #include "base/prefs/public/pref_change_registrar.h"
+#include "base/prefs/public/pref_observer.h"
 #include "chrome/browser/background/background_application_list_model.h"
 #include "chrome/browser/profiles/profile_info_cache_observer.h"
 #include "chrome/browser/profiles/profile_keyed_service.h"
 #include "chrome/browser/status_icons/status_icon.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 #include "ui/base/models/simple_menu_model.h"
 
 class Browser;
 class CommandLine;
@@ skipping 18 matching lines @@
 //
 // When Chrome is in background mode, it will continue running even after the
 // last browser window is closed, until the user explicitly exits the app.
 // Additionally, when in background mode, Chrome will launch on OS login with
 // no open windows to allow apps with the "background" permission to run in the
 // background.
 class BackgroundModeManager
     : public content::NotificationObserver,
       public BackgroundApplicationListModel::Observer,
       public ProfileInfoCacheObserver,
+      public PrefObserver,
       public ui::SimpleMenuModel::Delegate {
  public:
   BackgroundModeManager(CommandLine* command_line,
                         ProfileInfoCache* profile_cache);
   virtual ~BackgroundModeManager();
 
   static void RegisterPrefs(PrefService* prefs);
 
   virtual void RegisterProfile(Profile* profile);
 
@@ skipping 91 matching lines @@
   // which is similar to a shared_ptr.
   typedef linked_ptr<BackgroundModeData> BackgroundModeInfo;
 
   typedef std::map<Profile*, BackgroundModeInfo> BackgroundModeInfoMap;
 
   // content::NotificationObserver implementation.
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
+  // PrefObserver implementation.
+  virtual void OnPreferenceChanged(PrefServiceBase* service,
+                                   const std::string& pref_name) OVERRIDE;
+
   // Called when the kBackgroundModeEnabled preference changes.
   void OnBackgroundModeEnabledPrefChanged();
 
   // BackgroundApplicationListModel::Observer implementation.
   virtual void OnApplicationDataChanged(const extensions::Extension* extension,
                                         Profile* profile) OVERRIDE;
   virtual void OnApplicationListChanged(Profile* profile) OVERRIDE;
 
   // Overrides from ProfileInfoCacheObserver
   virtual void OnProfileAdded(const FilePath& profile_path) OVERRIDE;
@@ skipping 132 matching lines @@
   // app).
   bool keep_alive_for_test_;
 
   // Provides a command id for each profile as they are created.
   int current_command_id_;
 
   DISALLOW_COPY_AND_ASSIGN(BackgroundModeManager);
 };
 
 #endif  // CHROME_BROWSER_BACKGROUND_BACKGROUND_MODE_MANAGER_H_