Move Singleton and related structs to namespace base

ios/chrome/browser/favicon/favicon_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/favicon/favicon_service_factory.h"
 
 #include "base/memory/singleton.h"
 #include "components/favicon/core/favicon_service.h"
 #include "components/keyed_service/core/service_access_type.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
@@ skipping 16 matching lines @@
             browser_state->GetOriginalChromeBrowserState(), true));
   }
 
   // ios::ChromeBrowserState is OffTheRecord without access.
   NOTREACHED() << "ChromeBrowserState is OffTheRecord";
   return nullptr;
 }
 
 // static
 FaviconServiceFactory* FaviconServiceFactory::GetInstance() {
-  return Singleton<FaviconServiceFactory>::get();
+  return base::Singleton<FaviconServiceFactory>::get();
 }
 
 FaviconServiceFactory::FaviconServiceFactory()
     : BrowserStateKeyedServiceFactory(
           "FaviconService",
           BrowserStateDependencyManager::GetInstance()) {
   DependsOn(ios::HistoryServiceFactory::GetInstance());
 }
 
 FaviconServiceFactory::~FaviconServiceFactory() {
 }
 
 scoped_ptr<KeyedService> FaviconServiceFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   ios::ChromeBrowserState* browser_state =
       ios::ChromeBrowserState::FromBrowserState(context);
   return make_scoped_ptr(new favicon::FaviconService(
       make_scoped_ptr(new FaviconClientImpl),
       ios::HistoryServiceFactory::GetForBrowserState(
           browser_state, ServiceAccessType::EXPLICIT_ACCESS)));
 }
 
 bool FaviconServiceFactory::ServiceIsNULLWhileTesting() const {
   return true;
 }
 
 }  // namespace ios