Move Singleton and related structs to namespace base

chrome/browser/extensions/extension_sync_service_factory.cc

 // Copyright 2013 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/extensions/extension_sync_service_factory.h"
 
 #include "base/prefs/pref_service.h"
 #include "chrome/browser/extensions/extension_sync_service.h"
 #include "chrome/browser/extensions/extension_system_factory.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "extensions/browser/extension_prefs_factory.h"
 #include "extensions/browser/extension_registry_factory.h"
 #include "extensions/browser/extension_system.h"
 #include "extensions/browser/extensions_browser_client.h"
 
 // static
 ExtensionSyncService* ExtensionSyncServiceFactory::GetForBrowserContext(
     content::BrowserContext* context) {
   return static_cast<ExtensionSyncService*>(
       GetInstance()->GetServiceForBrowserContext(context, true));
 }
 
 // static
 ExtensionSyncServiceFactory* ExtensionSyncServiceFactory::GetInstance() {
-  return Singleton<ExtensionSyncServiceFactory>::get();
+  return base::Singleton<ExtensionSyncServiceFactory>::get();
 }
 
 ExtensionSyncServiceFactory::ExtensionSyncServiceFactory()
     : BrowserContextKeyedServiceFactory(
         "ExtensionSyncService",
         BrowserContextDependencyManager::GetInstance()) {
   DependsOn(extensions::ExtensionPrefsFactory::GetInstance());
   DependsOn(extensions::ExtensionRegistryFactory::GetInstance());
   DependsOn(extensions::ExtensionSystemFactory::GetInstance());
 }
 
 ExtensionSyncServiceFactory::~ExtensionSyncServiceFactory() {}
 
 KeyedService* ExtensionSyncServiceFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
   return new ExtensionSyncService(Profile::FromBrowserContext(context));
 }
 
 content::BrowserContext* ExtensionSyncServiceFactory::GetBrowserContextToUse(
     content::BrowserContext* context) const {
   return extensions::ExtensionsBrowserClient::Get()->
       GetOriginalContext(context);
 }