Move Singleton and related structs to namespace base

chrome/browser/search_engines/template_url_fetcher_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_SEARCH_ENGINES_TEMPLATE_URL_FETCHER_FACTORY_H_
 #define CHROME_BROWSER_SEARCH_ENGINES_TEMPLATE_URL_FETCHER_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 class Profile;
 class TemplateURLFetcher;
 
 // Singleton that owns all TemplateURLFetcher and associates them with
 // Profiles.
 class TemplateURLFetcherFactory : public BrowserContextKeyedServiceFactory {
  public:
   static TemplateURLFetcher* GetForProfile(Profile* profile);
 
   static TemplateURLFetcherFactory* GetInstance();
 
   // In some tests, the template url fetcher needs to be shutdown to
   // remove any dangling url requests before the io_thread is shutdown
   // to prevent leaks.
   static void ShutdownForProfile(Profile* profile);
 
  private:
-  friend struct DefaultSingletonTraits<TemplateURLFetcherFactory>;
+  friend struct base::DefaultSingletonTraits<TemplateURLFetcherFactory>;
 
   TemplateURLFetcherFactory();
   ~TemplateURLFetcherFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
 
   DISALLOW_COPY_AND_ASSIGN(TemplateURLFetcherFactory);
 };
 
 #endif  // CHROME_BROWSER_SEARCH_ENGINES_TEMPLATE_URL_FETCHER_FACTORY_H_