Move Singleton and related structs to namespace base

chrome/browser/search/suggestions/suggestions_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_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 class Profile;
 
 namespace suggestions {
 
 class SuggestionsService;
 
 // Singleton that owns all SuggestionsServices and associates them with
 // Profiles.
 class SuggestionsServiceFactory : public BrowserContextKeyedServiceFactory {
  public:
   // Returns the SuggestionsService for |profile|.
   static suggestions::SuggestionsService* GetForProfile(Profile* profile);
 
   static SuggestionsServiceFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<SuggestionsServiceFactory>;
+  friend struct base::DefaultSingletonTraits<SuggestionsServiceFactory>;
 
   SuggestionsServiceFactory();
   ~SuggestionsServiceFactory() override;
 
   // Overrides from BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   void RegisterProfilePrefs(
       user_prefs::PrefRegistrySyncable* registry) override;
 
   DISALLOW_COPY_AND_ASSIGN(SuggestionsServiceFactory);
 };
 
 }  // namespace suggestions
 
 #endif  // CHROME_BROWSER_SEARCH_SUGGESTIONS_SUGGESTIONS_SERVICE_FACTORY_H_