Screenshot effect non-obvious

chrome/browser/notifications/message_center_notification_manager.cc

 // 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.
 
 #include "chrome/browser/notifications/message_center_notification_manager.h"
 
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/extensions/extension_service.h"
@@ skipping 347 matching lines @@
 }
 
 void MessageCenterNotificationManager::ProfileNotification::StartDownloads() {
   downloads_->StartDownloads(notification_);
 }
 
 std::string
     MessageCenterNotificationManager::ProfileNotification::GetExtensionId() {
   const ExtensionURLInfo url(notification().origin_url());
   const ExtensionService* service = profile()->GetExtensionService();
-  const extensions::Extension* extension =
-      service->extensions()->GetExtensionOrAppByURL(url);
+  const extensions::Extension* extension = service ?
+      service->extensions()->GetExtensionOrAppByURL(url) : NULL;
   return extension ? extension->id() : std::string();
 }
 
 ////////////////////////////////////////////////////////////////////////////////
 // private
 
 void MessageCenterNotificationManager::AddProfileNotification(
     ProfileNotification* profile_notification) {
   const Notification& notification = profile_notification->notification();
   std::string id = notification.notification_id();
@@ skipping 24 matching lines @@
 
 MessageCenterNotificationManager::ProfileNotification*
     MessageCenterNotificationManager::FindProfileNotification(
         const std::string& id) const {
   NotificationMap::const_iterator iter = profile_notifications_.find(id);
   // If the notification is shown in UI, it must be in the map.
   DCHECK(iter != profile_notifications_.end());
   DCHECK((*iter).second);
   return (*iter).second;
 }