Remove the OnError method from notification delegates.

chrome/browser/chromeos/file_system_provider/notification_manager.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_CHROMEOS_FILE_SYSTEM_PROVIDER_NOTIFICATION_MANAGER_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_NOTIFICATION_MANAGER_H_
 
 #include <map>
 #include <string>
 
@@ skipping 29 matching lines @@
 
   // NotificationManagerInterface overrides:
   virtual void ShowUnresponsiveNotification(
       int id,
       const NotificationCallback& callback) override;
   virtual void HideUnresponsiveNotification(int id) override;
 
   // Invoked when a button on the notification is clicked.
   void OnButtonClick(int button_index);
 
-  // Invoked when the notification failed to show up.
-  void OnError();
-
   // Invoked when the notification got closed either by user or by system.
   void OnClose();
 
   // extensions::AppIconLoader::Delegate overrides:
   virtual void SetAppImage(const std::string& id,
                            const gfx::ImageSkia& image) override;
 
  private:
   typedef std::map<int, NotificationCallback> CallbackMap;
 
@@ skipping 10 matching lines @@
   scoped_ptr<extensions::AppIconLoader> icon_loader_;
   scoped_ptr<gfx::Image> extension_icon_;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationManager);
 };
 
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_NOTIFICATION_MANAGER_H_