Move Singleton and related structs to namespace base

chrome/browser/thumbnails/thumbnail_service_factory.h

 // 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.
 
 #ifndef CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_FACTORY_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/refcounted_browser_context_keyed_service_factory.h"
@@ skipping 13 matching lines @@
   // Depending on the settings, the implementation of the service interface
   // can be provided either by TopSites (stored in the profile itself) or
   // be an instance of a real RefcountedKeyedService
   // implementation.
   static scoped_refptr<thumbnails::ThumbnailService> GetForProfile(
       Profile* profile);
 
   static ThumbnailServiceFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<ThumbnailServiceFactory>;
+  friend struct base::DefaultSingletonTraits<ThumbnailServiceFactory>;
 
   ThumbnailServiceFactory();
   ~ThumbnailServiceFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   scoped_refptr<RefcountedKeyedService> BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
 
   DISALLOW_COPY_AND_ASSIGN(ThumbnailServiceFactory);
 };
 
 #endif  // CHROME_BROWSER_THUMBNAILS_THUMBNAIL_SERVICE_FACTORY_H_