Move Singleton and related structs to namespace base

ios/chrome/browser/signin/about_signin_internals_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/about_signin_internals_factory.h"
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/signin/core/browser/about_signin_internals.h"
 #include "ios/chrome/browser/signin/account_tracker_service_factory.h"
@@ skipping 22 matching lines @@
 
 // static
 AboutSigninInternals* AboutSigninInternalsFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return static_cast<AboutSigninInternals*>(
       GetInstance()->GetServiceForBrowserState(browser_state, true));
 }
 
 // static
 AboutSigninInternalsFactory* AboutSigninInternalsFactory::GetInstance() {
-  return Singleton<AboutSigninInternalsFactory>::get();
+  return base::Singleton<AboutSigninInternalsFactory>::get();
 }
 
 scoped_ptr<KeyedService> AboutSigninInternalsFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   ios::ChromeBrowserState* chrome_browser_state =
       ios::ChromeBrowserState::FromBrowserState(context);
   scoped_ptr<AboutSigninInternals> service(new AboutSigninInternals(
       OAuth2TokenServiceFactory::GetForBrowserState(chrome_browser_state),
       AccountTrackerServiceFactory::GetForBrowserState(chrome_browser_state),
       SigninManagerFactory::GetForBrowserState(chrome_browser_state),
       SigninErrorControllerFactory::GetForBrowserState(chrome_browser_state),
       GaiaCookieManagerServiceFactory::GetForBrowserState(
           chrome_browser_state)));
   service->Initialize(
       SigninClientFactory::GetForBrowserState(chrome_browser_state));
   return service.Pass();
 }
 
 void AboutSigninInternalsFactory::RegisterBrowserStatePrefs(
     user_prefs::PrefRegistrySyncable* user_prefs) {
   AboutSigninInternals::RegisterPrefs(user_prefs);
 }
 
 }  // namespace ios