Move Singleton and related structs to namespace base

chrome/browser/signin/account_tracker_service_factory.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_SIGNIN_ACCOUNT_TRACKER_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_SIGNIN_ACCOUNT_TRACKER_SERVICE_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 class AccountTrackerService;
 class Profile;
 
 // Singleton that owns all AccountTrackerServices and associates them with
 // Profiles. Listens for the Profile's destruction notification and cleans up
 // the associated AccountTrackerService.
 class AccountTrackerServiceFactory
     : public BrowserContextKeyedServiceFactory {
  public:
   // Returns the instance of AccountTrackerService associated with this
   // profile (creating one if none exists). Returns NULL if this profile
   // cannot have a AccountTrackerService (for example, if |profile| is
   // incognito).
   static AccountTrackerService* GetForProfile(Profile* profile);
 
   // Returns an instance of the AccountTrackerServiceFactory singleton.
   static AccountTrackerServiceFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<AccountTrackerServiceFactory>;
+  friend struct base::DefaultSingletonTraits<AccountTrackerServiceFactory>;
 
   AccountTrackerServiceFactory();
   ~AccountTrackerServiceFactory() override;
 
   // BrowserContextKeyedServiceFactory implementation.
   void RegisterProfilePrefs(
       user_prefs::PrefRegistrySyncable* registry) override;
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
 
   DISALLOW_COPY_AND_ASSIGN(AccountTrackerServiceFactory);
 };
 
 #endif  // CHROME_BROWSER_SIGNIN_ACCOUNT_TRACKER_SERVICE_FACTORY_H_