[Notifications] Fix crash in AddNotification.

ui/message_center/views/message_center_view.h

 // Copyright (c) 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.
 
 #ifndef UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_VIEW_H_
 #define UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_VIEW_H_
 
 #include <stddef.h>
 
 #include "base/macros.h"
@@ skipping 104 matching lines @@
 
   static bool disable_animation_for_testing;
 
   void AddNotificationAt(const Notification& notification, int index);
   base::string16 GetButtonBarTitle() const;
   void Update(bool animate);
   void SetVisibilityMode(Mode mode, bool animate);
   void UpdateButtonBarStatus();
   void EnableCloseAllIfAppropriate();
   void SetNotificationViewForTest(MessageView* view);
+  void UpdateNotification(const std::string& notification_id);
 
   MessageCenter* message_center_;  // Weak reference.
   MessageCenterTray* tray_;  // Weak reference.
 
   // Map notification_id->MessageView*. It contains all MessageViews currently
   // displayed in MessageCenter.
   typedef std::map<std::string, MessageView*> NotificationViewsMap;
   NotificationViewsMap notification_views_;  // Weak.
 
   // Child views.
@@ skipping 29 matching lines @@
   std::unique_ptr<MessageViewContextMenuController> context_menu_controller_;
 
   views::FocusManager* focus_manager_ = nullptr;
 
   DISALLOW_COPY_AND_ASSIGN(MessageCenterView);
 };
 
 }  // namespace message_center
 
 #endif  // UI_MESSAGE_CENTER_VIEWS_MESSAGE_CENTER_VIEW_H_