Move Singleton and related structs to namespace base

ios/chrome/browser/history/top_sites_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/history/top_sites_factory.h"
 
 #include "base/memory/singleton.h"
 #include "components/history/core/browser/history_constants.h"
 #include "components/history/core/browser/top_sites_impl.h"
 #include "components/keyed_service/core/refcounted_keyed_service.h"
 #include "components/keyed_service/core/service_access_type.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/pref_registry/pref_registry_syncable.h"
 #include "ios/chrome/browser/history/history_service_factory.h"
 #include "ios/chrome/browser/history/history_utils.h"
 #include "ios/public/provider/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/web/public/web_thread.h"
 
 namespace ios {
 
 // static
 scoped_refptr<history::TopSites> TopSitesFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return make_scoped_refptr(static_cast<history::TopSites*>(
       GetInstance()->GetServiceForBrowserState(browser_state, true).get()));
 }
 
 // static
 TopSitesFactory* TopSitesFactory::GetInstance() {
-  return Singleton<TopSitesFactory>::get();
+  return base::Singleton<TopSitesFactory>::get();
 }
 
 TopSitesFactory::TopSitesFactory()
     : RefcountedBrowserStateKeyedServiceFactory(
           "TopSites",
           BrowserStateDependencyManager::GetInstance()) {
   DependsOn(ios::HistoryServiceFactory::GetInstance());
 }
 
 TopSitesFactory::~TopSitesFactory() {
@@ skipping 17 matching lines @@
 void TopSitesFactory::RegisterBrowserStatePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   history::TopSitesImpl::RegisterPrefs(registry);
 }
 
 bool TopSitesFactory::ServiceIsNULLWhileTesting() const {
   return true;
 }
 
 }  // namespace ios