[sync] Isolate FOREIGN_SESSION_UPDATED notification in ProfileSyncService

chrome/browser/ui/webui/foreign_session_handler.h

 // Copyright 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_FOREIGN_SESSION_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_FOREIGN_SESSION_HANDLER_H_
 
 #include <vector>
 
 #include "base/scoped_observer.h"
 #include "base/time/time.h"
 #include "chrome/browser/sessions/session_service.h"
 #include "components/sync_driver/open_tabs_ui_delegate.h"
 #include "components/sync_driver/sync_service_observer.h"
-#include "content/public/browser/notification_observer.h"
-#include "content/public/browser/notification_registrar.h"
 #include "content/public/browser/web_ui.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
 namespace sessions {
 struct SessionTab;
 struct SessionWindow;
 }
 
 namespace sync_driver {
 class SyncService;
 }
 
 namespace user_prefs {
 class PrefRegistrySyncable;
 }
 
 namespace browser_sync {
 
 class ForeignSessionHandler : public content::WebUIMessageHandler,
-                              public content::NotificationObserver,
                               public sync_driver::SyncServiceObserver {
  public:
   // Invalid value, used to note that we don't have a tab or window number.
   static const int kInvalidId = -1;
 
   // WebUIMessageHandler implementation.
   void RegisterMessages() override;
 
   ForeignSessionHandler();
   ~ForeignSessionHandler() override;
 
   static void RegisterProfilePrefs(user_prefs::PrefRegistrySyncable* registry);
 
   static void OpenForeignSessionTab(content::WebUI* web_ui,
                                     const std::string& session_string_value,
                                     SessionID::id_type window_num,
                                     SessionID::id_type tab_id,
                                     const WindowOpenDisposition& disposition);
 
   static void OpenForeignSessionWindows(content::WebUI* web_ui,
                                         const std::string& session_string_value,
                                         SessionID::id_type window_num);
 
   // Returns a pointer to the current session model associator or NULL.
   static sync_driver::OpenTabsUIDelegate* GetOpenTabsUIDelegate(
       content::WebUI* web_ui);
 
  private:
-  // Determines how ForeignSessionHandler will interact with the new tab page.
-  void Observe(int type,
-               const content::NotificationSource& source,
-               const content::NotificationDetails& details) override;
-
   // sync_driver::SyncServiceObserver:
   void OnStateChanged() override {}
   void OnSyncConfigurationCompleted() override;
+  void OnForeignSessionUpdated() override;
 
   // Returns true if tab sync is enabled for this profile, otherwise false.
   bool IsTabSyncEnabled();
 
   // Returns a string used to show the user when a session was last modified.
   base::string16 FormatSessionTime(const base::Time& time);
 
   // Determines which session is to be opened, and then calls
   // OpenForeignSession, to begin the process of opening a new browser window.
   // This is a javascript callback handler.
   void HandleOpenForeignSession(const base::ListValue* args);
 
   // Determines whether foreign sessions should be obtained from the sync model.
   // This is a javascript callback handler, and it is also called when the sync
   // model has changed and the new tab page needs to reflect the changes.
   void HandleGetForeignSessions(const base::ListValue* args);
 
   // Delete a foreign session. This will remove it from the list of foreign
   // sessions on all devices. It will reappear if the session is re-activated
   // on the original device.
   // This is a javascript callback handler.
   void HandleDeleteForeignSession(const base::ListValue* args);
 
   void HandleSetForeignSessionCollapsed(const base::ListValue* args);
 
-  // The Registrar used to register ForeignSessionHandler for notifications.
-  content::NotificationRegistrar registrar_;
-
   // ScopedObserver used to observe the ProfileSyncService.
   ScopedObserver<sync_driver::SyncService, sync_driver::SyncServiceObserver>
       scoped_observer_;
 
   // The time at which this WebUI was created. Used to calculate how long
   // the WebUI was present before the sessions data was visible.
   base::TimeTicks load_attempt_time_;
 
   DISALLOW_COPY_AND_ASSIGN(ForeignSessionHandler);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_UI_WEBUI_FOREIGN_SESSION_HANDLER_H_