Move Singleton and related structs to namespace base

ios/chrome/browser/signin/oauth2_token_service_factory.cc

 // Copyright 2015 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 "ios/chrome/browser/signin/oauth2_token_service_factory.h"
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
@@ skipping 17 matching lines @@
 OAuth2TokenServiceFactory::~OAuth2TokenServiceFactory() {}
 
 ProfileOAuth2TokenService* OAuth2TokenServiceFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return static_cast<ProfileOAuth2TokenService*>(
       GetInstance()->GetServiceForBrowserState(browser_state, true));
 }
 
 // static
 OAuth2TokenServiceFactory* OAuth2TokenServiceFactory::GetInstance() {
-  return Singleton<OAuth2TokenServiceFactory>::get();
+  return base::Singleton<OAuth2TokenServiceFactory>::get();
 }
 
 void OAuth2TokenServiceFactory::RegisterBrowserStatePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   registry->RegisterBooleanPref(prefs::kTokenServiceExcludeAllSecondaryAccounts,
                                 false);
   registry->RegisterListPref(prefs::kTokenServiceExcludedSecondaryAccounts);
 }
 
 scoped_ptr<KeyedService> OAuth2TokenServiceFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   ios::ChromeBrowserState* chrome_browser_state =
       ios::ChromeBrowserState::FromBrowserState(context);
   ProfileOAuth2TokenServiceIOSDelegate* delegate =
       new ProfileOAuth2TokenServiceIOSDelegate(
           SigninClientFactory::GetForBrowserState(chrome_browser_state),
           ios::GetChromeBrowserProvider()
               ->GetProfileOAuth2TokenServiceIOSProvider(),
           ios::AccountTrackerServiceFactory::GetForBrowserState(
               chrome_browser_state),
           ios::SigninErrorControllerFactory::GetForBrowserState(
               chrome_browser_state));
   return make_scoped_ptr(new ProfileOAuth2TokenService(delegate));
 }