Remove the OnError method from notification delegates.

chrome/browser/ui/cocoa/apps/quit_with_apps_controller_mac.h

 // Copyright 2014 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_COCOA_APPS_QUIT_WITH_APPS_CONTROLLER_MAC_H_
 #define CHROME_BROWSER_UI_COCOA_APPS_QUIT_WITH_APPS_CONTROLLER_MAC_H_
 
 #include "base/macros.h"
 #include "base/memory/scoped_ptr.h"
 #include "chrome/browser/notifications/notification.h"
 
 class PrefRegistrySimple;
 class Profile;
 
 // QuitWithAppsController checks whether any apps are running and shows a
 // notification to quit all of them.
 class QuitWithAppsController : public NotificationDelegate {
  public:
   static const char kQuitWithAppsNotificationID[];
 
   QuitWithAppsController();
 
   // NotificationDelegate interface.
   void Display() override;
-  void Error() override;
   void Close(bool by_user) override;
   void Click() override;
   void ButtonClick(int button_index) override;
   std::string id() const override;
 
   // Attempt to quit Chrome. This will display a notification and return false
   // if there are apps running.
   bool ShouldQuit();
 
   // Register prefs used by QuitWithAppsController.
   static void RegisterPrefs(PrefRegistrySimple* registry);
 
  private:
   ~QuitWithAppsController() override;
 
   scoped_ptr<Notification> notification_;
   // The Profile instance associated with the notification_. We need to cache
   // the instance here because when we want to cancel the notification we need
   // to provide the profile which was used to add the notification previously.
   // Not owned by this class.
   Profile* notification_profile_;
 
   // Whether to suppress showing the notification for the rest of the session.
   bool suppress_for_session_;
 
   DISALLOW_COPY_AND_ASSIGN(QuitWithAppsController);
 };
 
 #endif  // CHROME_BROWSER_UI_COCOA_APPS_QUIT_WITH_APPS_CONTROLLER_MAC_H_