Move Singleton and related structs to namespace base

ios/chrome/browser/search_engines/template_url_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/search_engines/template_url_service_factory.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/core/service_access_type.h"
@@ skipping 46 matching lines @@
 
 // static
 TemplateURLService* TemplateURLServiceFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return static_cast<TemplateURLService*>(
       GetInstance()->GetServiceForBrowserState(browser_state, true));
 }
 
 // static
 TemplateURLServiceFactory* TemplateURLServiceFactory::GetInstance() {
-  return Singleton<TemplateURLServiceFactory>::get();
+  return base::Singleton<TemplateURLServiceFactory>::get();
 }
 
 // static
 BrowserStateKeyedServiceFactory::TestingFactoryFunction
 TemplateURLServiceFactory::GetDefaultFactory() {
   return &BuildTemplateURLService;
 }
 
 TemplateURLServiceFactory::TemplateURLServiceFactory()
     : BrowserStateKeyedServiceFactory(
@@ skipping 20 matching lines @@
 web::BrowserState* TemplateURLServiceFactory::GetBrowserStateToUse(
     web::BrowserState* context) const {
   return GetBrowserStateRedirectedInIncognito(context);
 }
 
 bool TemplateURLServiceFactory::ServiceIsNULLWhileTesting() const {
   return true;
 }
 
 }  // namespace ios