Move Singleton and related structs to namespace base

content/browser/notifications/notification_event_dispatcher_impl.h

 // Copyright 2014 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 CONTENT_BROWSER_NOTIFICATIONS_NOTIFICATION_EVENT_DISPATCHER_IMPL_H_
 #define CONTENT_BROWSER_NOTIFICATIONS_NOTIFICATION_EVENT_DISPATCHER_IMPL_H_
 
 #include "base/memory/singleton.h"
 #include "content/public/browser/notification_event_dispatcher.h"
 
@@ skipping 11 matching lines @@
       int64_t persistent_notification_id,
       const GURL& origin,
       int action_index,
       const NotificationClickDispatchCompleteCallback&
           dispatch_complete_callback) override;
 
  private:
   NotificationEventDispatcherImpl();
   ~NotificationEventDispatcherImpl() override;
 
-  friend struct DefaultSingletonTraits<NotificationEventDispatcherImpl>;
+  friend struct base::DefaultSingletonTraits<NotificationEventDispatcherImpl>;
 
   DISALLOW_COPY_AND_ASSIGN(NotificationEventDispatcherImpl);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_NOTIFICATIONS_NOTIFICATION_EVENT_DISPATCHER_IMPL_H_