Move Singleton and related structs to namespace base

chrome/browser/ui/webui/ntp/ntp_resource_cache_factory.h

 // Copyright (c) 2011 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_UI_WEBUI_NTP_NTP_RESOURCE_CACHE_FACTORY_H_
 #define CHROME_BROWSER_UI_WEBUI_NTP_NTP_RESOURCE_CACHE_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 class NTPResourceCache;
 class Profile;
 
 // Singleton that owns the NTPResourceCaches used by the NTP and associates them
 // with Profiles. Listens for the Profile's destruction notification and cleans
 // up the associated ThemeService.
 class NTPResourceCacheFactory : public BrowserContextKeyedServiceFactory {
  public:
   static NTPResourceCache* GetForProfile(Profile* profile);
 
   static NTPResourceCacheFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<NTPResourceCacheFactory>;
+  friend struct base::DefaultSingletonTraits<NTPResourceCacheFactory>;
 
   NTPResourceCacheFactory();
   ~NTPResourceCacheFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_NTP_NTP_RESOURCE_CACHE_FACTORY_H_