Move Singleton and related structs to namespace base

chrome/browser/storage/durable_storage_permission_context_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 "chrome/browser/storage/durable_storage_permission_context_factory.h"
 
 #include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/storage/durable_storage_permission_context.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 
 // static
 DurableStoragePermissionContext*
 DurableStoragePermissionContextFactory::GetForProfile(Profile* profile) {
   return static_cast<DurableStoragePermissionContext*>(
       GetInstance()->GetServiceForBrowserContext(profile, true));
 }
 
 // static
 DurableStoragePermissionContextFactory*
 DurableStoragePermissionContextFactory::GetInstance() {
-  return Singleton<DurableStoragePermissionContextFactory>::get();
+  return base::Singleton<DurableStoragePermissionContextFactory>::get();
 }
 
 DurableStoragePermissionContextFactory::DurableStoragePermissionContextFactory()
     : BrowserContextKeyedServiceFactory(
           "DurableStoragePermissionContext",
           BrowserContextDependencyManager::GetInstance()) {
 }
 
 KeyedService* DurableStoragePermissionContextFactory::BuildServiceInstanceFor(
     content::BrowserContext* profile) const {
   return new DurableStoragePermissionContext(static_cast<Profile*>(profile));
 }
 
 content::BrowserContext*
 DurableStoragePermissionContextFactory::GetBrowserContextToUse(
     content::BrowserContext* context) const {
   return chrome::GetBrowserContextOwnInstanceInIncognito(context);
 }