Move Singleton and related structs to namespace base

chrome/browser/autofill/personal_data_manager_factory.h

 // Copyright (c) 2011 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_AUTOFILL_PERSONAL_DATA_MANAGER_FACTORY_H_
 #define CHROME_BROWSER_AUTOFILL_PERSONAL_DATA_MANAGER_FACTORY_H_
 
 #include "base/compiler_specific.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 #include "components/keyed_service/core/keyed_service.h"
 
+namespace base {
 template <typename T> struct DefaultSingletonTraits;
+}
+
 class Profile;
 
 namespace autofill {
 
 class PersonalDataManager;
 
 // Singleton that owns all PersonalDataManagers and associates them with
 // Profiles.
 // Listens for the Profile's destruction notification and cleans up the
 // associated PersonalDataManager.
 class PersonalDataManagerFactory : public BrowserContextKeyedServiceFactory {
  public:
   // Returns the PersonalDataManager for |profile|, creating it if it is not
   // yet created.
   static PersonalDataManager* GetForProfile(Profile* profile);
 
   static PersonalDataManagerFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<PersonalDataManagerFactory>;
+  friend struct base::DefaultSingletonTraits<PersonalDataManagerFactory>;
 
   PersonalDataManagerFactory();
   ~PersonalDataManagerFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
 };
 
 }  // namespace autofill
 
 #endif  // CHROME_BROWSER_AUTOFILL_PERSONAL_DATA_MANAGER_FACTORY_H_