Move Singleton and related structs to namespace base

chrome/browser/extensions/token_cache/token_cache_service_factory.h

 // Copyright (c) 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_EXTENSIONS_TOKEN_CACHE_TOKEN_CACHE_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_EXTENSIONS_TOKEN_CACHE_TOKEN_CACHE_SERVICE_FACTORY_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 class Profile;
 
 namespace extensions {
 class TokenCacheService;
 }  // namespace extensions
 
 class TokenCacheServiceFactory : public BrowserContextKeyedServiceFactory {
  public:
   static extensions::TokenCacheService* GetForProfile(Profile* profile);
   static TokenCacheServiceFactory* GetInstance();
 
  private:
   TokenCacheServiceFactory();
   ~TokenCacheServiceFactory() override;
 
-  friend struct DefaultSingletonTraits<TokenCacheServiceFactory>;
+  friend struct base::DefaultSingletonTraits<TokenCacheServiceFactory>;
 
   // Inherited from BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
 
    DISALLOW_COPY_AND_ASSIGN(TokenCacheServiceFactory);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_TOKEN_CACHE_TOKEN_CACHE_SERVICE_FACTORY_H_