Move Singleton and related structs to namespace base

chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service_factory.cc

 // 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.
 
 #include "chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service_factory.h"
 
 #include "chrome/browser/supervised_user/legacy/supervised_user_shared_settings_service.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "components/user_prefs/user_prefs.h"
 #include "content/public/browser/browser_context.h"
 
 // static
 SupervisedUserSharedSettingsService*
 SupervisedUserSharedSettingsServiceFactory::GetForBrowserContext(
     content::BrowserContext* profile) {
   return static_cast<SupervisedUserSharedSettingsService*>(
       GetInstance()->GetServiceForBrowserContext(profile, true));
 }
 
 // static
 SupervisedUserSharedSettingsServiceFactory*
 SupervisedUserSharedSettingsServiceFactory::GetInstance() {
-  return Singleton<SupervisedUserSharedSettingsServiceFactory>::get();
+  return base::Singleton<SupervisedUserSharedSettingsServiceFactory>::get();
 }
 
 SupervisedUserSharedSettingsServiceFactory::
     SupervisedUserSharedSettingsServiceFactory()
     : BrowserContextKeyedServiceFactory(
           "SupervisedUserSharedSettingsService",
           BrowserContextDependencyManager::GetInstance()) {}
 
 SupervisedUserSharedSettingsServiceFactory::
     ~SupervisedUserSharedSettingsServiceFactory() {}
 
 KeyedService*
 SupervisedUserSharedSettingsServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* profile) const {
   return new SupervisedUserSharedSettingsService(
       user_prefs::UserPrefs::Get(profile));
 }