Remove the OnError method from notification delegates.

ash/system/locale/locale_notification_controller.cc

 // Copyright 2013 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.
 
 #include "ash/system/locale/locale_notification_controller.h"
 
 #include "ash/shell.h"
 #include "ash/system/system_notifier.h"
 #include "ash/system/tray/system_tray_notifier.h"
 #include "base/strings/string16.h"
@@ skipping 15 matching lines @@
 
 class LocaleNotificationDelegate : public message_center::NotificationDelegate {
  public:
   explicit LocaleNotificationDelegate(LocaleObserver::Delegate* delegate);
 
  protected:
   ~LocaleNotificationDelegate() override;
 
   // message_center::NotificationDelegate overrides:
   void Display() override;
-  void Error() override;
   void Close(bool by_user) override;
   bool HasClickedListener() override;
   void Click() override;
   void ButtonClick(int button_index) override;
 
  private:
   LocaleObserver::Delegate* delegate_;
 
   DISALLOW_COPY_AND_ASSIGN(LocaleNotificationDelegate);
 };
 
 LocaleNotificationDelegate::LocaleNotificationDelegate(
     LocaleObserver::Delegate* delegate)
   : delegate_(delegate) {
   DCHECK(delegate_);
 }
 
 LocaleNotificationDelegate::~LocaleNotificationDelegate() {
 }
 
 void LocaleNotificationDelegate::Display() {
 }
 
-void LocaleNotificationDelegate::Error() {
-}
-
 void LocaleNotificationDelegate::Close(bool by_user) {
   delegate_->AcceptLocaleChange();
 }
 
 bool LocaleNotificationDelegate::HasClickedListener() {
   return true;
 }
 
 void LocaleNotificationDelegate::Click() {
   delegate_->AcceptLocaleChange();
@@ skipping 45 matching lines @@
       base::string16()  /* display_source */,
       message_center::NotifierId(
           message_center::NotifierId::SYSTEM_COMPONENT,
           system_notifier::kNotifierLocale),
       optional,
       new LocaleNotificationDelegate(delegate)));
   message_center::MessageCenter::Get()->AddNotification(notification.Pass());
 }
 
 }  // namespace ash