Move Singleton and related structs to namespace base

extensions/browser/updater/update_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 "extensions/browser/updater/update_service_factory.h"
 
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "extensions/browser/extension_registry_factory.h"
 #include "extensions/browser/process_manager_factory.h"
 #include "extensions/browser/updater/update_service.h"
 
 namespace extensions {
 
 // static
 UpdateService* UpdateServiceFactory::GetForBrowserContext(
     content::BrowserContext* context) {
   return static_cast<UpdateService*>(
       GetInstance()->GetServiceForBrowserContext(context, true));
 }
 
 // static
 UpdateServiceFactory* UpdateServiceFactory::GetInstance() {
-  return Singleton<UpdateServiceFactory>::get();
+  return base::Singleton<UpdateServiceFactory>::get();
 }
 
 UpdateServiceFactory::UpdateServiceFactory()
     : BrowserContextKeyedServiceFactory(
           "UpdateService",
           BrowserContextDependencyManager::GetInstance()) {
   DependsOn(extensions::ExtensionRegistryFactory::GetInstance());
   DependsOn(extensions::ProcessManagerFactory::GetInstance());
 }
 
 UpdateServiceFactory::~UpdateServiceFactory() {
 }
 
 KeyedService* UpdateServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
   return new UpdateService(context);
 }
 
 }  // namespace extensions