CrOS: Do not allow notifications to be added during shutdown.

chrome/browser/notifications/message_center_notification_manager.h

 // Copyright (c) 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_NOTIFICATIONS_MESSAGE_CENTER_NOTIFICATION_MANAGER_H_
 #define CHROME_BROWSER_NOTIFICATIONS_MESSAGE_CENTER_NOTIFICATION_MANAGER_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 41 matching lines @@
                                ProfileID profile_id) const override;
   bool CancelById(const std::string& delegate_id,
                   ProfileID profile_id) override;
   std::set<std::string> GetAllIdsByProfileAndSourceOrigin(
       ProfileID profile_id,
       const GURL& source) override;
   std::set<std::string> GetAllIdsByProfile(ProfileID profile_id) override;
   bool CancelAllBySourceOrigin(const GURL& source_origin) override;
   bool CancelAllByProfile(ProfileID profile_id) override;
   void CancelAll() override;
+  void StartShutdown() override;
 
   // MessageCenterObserver
   void OnNotificationRemoved(const std::string& notification_id,
                              bool by_user) override;
   void OnCenterVisibilityChanged(message_center::Visibility) override;
   void OnNotificationUpdated(const std::string& notification_id) override;
 
   void EnsureMessageCenterClosed();
 
   // Takes ownership of |delegate|.
@@ skipping 29 matching lines @@
   std::unique_ptr<message_center::NotifierSettingsProvider> settings_provider_;
 
   // To own the blockers.
   std::vector<std::unique_ptr<message_center::NotificationBlocker>> blockers_;
 
   NotificationSystemObserver system_observer_;
 
   // Keeps track of all notification statistics for UMA purposes.
   MessageCenterStatsCollector stats_collector_;
 
+  // Tracks if shutdown has started.
+  bool is_shutdown_started_ = false;
+
   DISALLOW_COPY_AND_ASSIGN(MessageCenterNotificationManager);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_MESSAGE_CENTER_NOTIFICATION_MANAGER_H_