Move Singleton and related structs to namespace base

ios/public/test/fake_sync_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/public/test/fake_sync_service_factory.h"
 
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
@@ skipping 13 matching lines @@
  private:
   sync_driver::FakeSyncService fake_sync_service_;
 };
 
 }  // namespace
 
 namespace ios {
 
 // static
 FakeSyncServiceFactory* FakeSyncServiceFactory::GetInstance() {
-  return Singleton<FakeSyncServiceFactory>::get();
+  return base::Singleton<FakeSyncServiceFactory>::get();
 }
 
 // static
 sync_driver::FakeSyncService* FakeSyncServiceFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return static_cast<KeyedFakeSyncService*>(
              FakeSyncServiceFactory::GetInstance()->GetServiceForBrowserState(
                  browser_state, true))->fake_sync_service();
 }
 
 FakeSyncServiceFactory::FakeSyncServiceFactory()
     : BrowserStateKeyedServiceFactory(
           "FakeSyncService",
           BrowserStateDependencyManager::GetInstance()) {
 }
 
 FakeSyncServiceFactory::~FakeSyncServiceFactory() {
 }
 
 scoped_ptr<KeyedService> FakeSyncServiceFactory::BuildServiceInstanceFor(
     web::BrowserState* context) const {
   return make_scoped_ptr(new KeyedFakeSyncService);
 }
 
 }  // namespace ios