Move Singleton and related structs to namespace base

chrome/browser/signin/signin_manager_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_SIGNIN_SIGNIN_MANAGER_FACTORY_H_
 #define CHROME_BROWSER_SIGNIN_SIGNIN_MANAGER_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "base/observer_list.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
@@ skipping 55 matching lines @@
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
   // Notifies observers of |manager|'s creation. Should be called only by test
   // SigninManager subclasses whose construction does not occur in
   // |BuildServiceInstanceFor()|.
   void NotifyObserversOfSigninManagerCreationForTesting(
       SigninManagerBase* manager);
 
  private:
-  friend struct DefaultSingletonTraits<SigninManagerFactory>;
+  friend struct base::DefaultSingletonTraits<SigninManagerFactory>;
 
   SigninManagerFactory();
   ~SigninManagerFactory() override;
 
   // List of observers. Checks that list is empty on destruction.
   mutable base::ObserverList<Observer, true> observer_list_;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   void BrowserContextShutdown(content::BrowserContext* context) override;
 };
 
 #endif  // CHROME_BROWSER_SIGNIN_SIGNIN_MANAGER_FACTORY_H_