Move Singleton and related structs to namespace base

chrome/browser/drive/drive_notification_manager_factory.h

 // Copyright 2013 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_DRIVE_DRIVE_NOTIFICATION_MANAGER_FACTORY_H_
 #define CHROME_BROWSER_DRIVE_DRIVE_NOTIFICATION_MANAGER_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
@@ skipping 16 matching lines @@
       content::BrowserContext* context);
 
   // Returns the |DriveNotificationManager| for |context|, creating it first if
   // required.
   static DriveNotificationManager* GetForBrowserContext(
       content::BrowserContext* context);
 
   static DriveNotificationManagerFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<DriveNotificationManagerFactory>;
+  friend struct base::DefaultSingletonTraits<DriveNotificationManagerFactory>;
 
   DriveNotificationManagerFactory();
   ~DriveNotificationManagerFactory() override;
 
   // BrowserContextKeyedServiceFactory implementation.
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_DRIVE_DRIVE_NOTIFICATION_MANAGER_FACTORY_H_