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

chrome/browser/notifications/message_center_notification_manager.cc

Index: chrome/browser/notifications/message_center_notification_manager.cc
diff --git a/chrome/browser/notifications/message_center_notification_manager.cc b/chrome/browser/notifications/message_center_notification_manager.cc
index e60cdd6f8c11a0a9b8e80ab4bde751eb77425501..9376d91c85f4f3bf6f0bd5f304b4cdee6c76b2ed 100644
--- a/chrome/browser/notifications/message_center_notification_manager.cc
+++ b/chrome/browser/notifications/message_center_notification_manager.cc
@@ -80,6 +80,10 @@ MessageCenterNotificationManager::~MessageCenterNotificationManager() {
 
 void MessageCenterNotificationManager::Add(const Notification& notification,
                                            Profile* profile) {
+  // We won't have time to process and act on this notification.
+  if (is_shutdown_started_)
+    return;
+
   if (Update(notification, profile))
     return;
 
@@ -257,6 +261,11 @@ void MessageCenterNotificationManager::CancelAll() {
       false /* by_user */, message_center::MessageCenter::RemoveType::ALL);
 }
 
+void MessageCenterNotificationManager::StartShutdown() {
+  is_shutdown_started_ = true;
+  CancelAll();
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // MessageCenter::Observer
 void MessageCenterNotificationManager::OnNotificationRemoved(