Move Singleton and related structs to namespace base

chrome/browser/notifications/platform_notification_service_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 CHROME_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_SERVICE_IMPL_H_
 #define CHROME_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_SERVICE_IMPL_H_
 
 #include <stdint.h>
 #include <map>
 #include <set>
@@ skipping 68 matching lines @@
       const SkBitmap& icon,
       const content::PlatformNotificationData& notification_data) override;
   void ClosePersistentNotification(
       content::BrowserContext* browser_context,
       int64_t persistent_notification_id) override;
   bool GetDisplayedPersistentNotifications(
       content::BrowserContext* browser_context,
       std::set<std::string>* displayed_notifications) override;
 
  private:
-  friend struct DefaultSingletonTraits<PlatformNotificationServiceImpl>;
+  friend struct base::DefaultSingletonTraits<PlatformNotificationServiceImpl>;
   friend class PlatformNotificationServiceBrowserTest;
   friend class PlatformNotificationServiceTest;
   friend class PushMessagingBrowserTest;
   FRIEND_TEST_ALL_PREFIXES(PlatformNotificationServiceTest,
                            CreateNotificationFromData);
   FRIEND_TEST_ALL_PREFIXES(PlatformNotificationServiceTest,
                            DisplayNameForContextMessage);
 
   PlatformNotificationServiceImpl();
   ~PlatformNotificationServiceImpl() override;
@@ skipping 20 matching lines @@
   NotificationUIManager* notification_ui_manager_for_tests_;
 
   // Mapping between a persistent notification id and the id of the associated
   // message_center::Notification object. Must only be used on the UI thread.
   std::map<int64_t, std::string> persistent_notifications_;
 
   DISALLOW_COPY_AND_ASSIGN(PlatformNotificationServiceImpl);
 };
 
 #endif  // CHROME_BROWSER_NOTIFICATIONS_PLATFORM_NOTIFICATION_SERVICE_IMPL_H_