Move Singleton and related structs to namespace base

extensions/browser/extension_pref_value_map_factory.cc

 // Copyright 2014 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 "extensions/browser/extension_pref_value_map_factory.h"
 
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "extensions/browser/extension_pref_value_map.h"
 #include "extensions/browser/extensions_browser_client.h"
 
 ExtensionPrefValueMapFactory::ExtensionPrefValueMapFactory()
     : BrowserContextKeyedServiceFactory(
         "ExtensionPrefValueMap",
         BrowserContextDependencyManager::GetInstance()) {
 }
 
 ExtensionPrefValueMapFactory::~ExtensionPrefValueMapFactory() {
 }
 
 // static
 ExtensionPrefValueMap* ExtensionPrefValueMapFactory::GetForBrowserContext(
     content::BrowserContext* context) {
   return static_cast<ExtensionPrefValueMap*>(
       GetInstance()->GetServiceForBrowserContext(context, true));
 }
 
 // static
 ExtensionPrefValueMapFactory* ExtensionPrefValueMapFactory::GetInstance() {
-  return Singleton<ExtensionPrefValueMapFactory>::get();
+  return base::Singleton<ExtensionPrefValueMapFactory>::get();
 }
 
 KeyedService* ExtensionPrefValueMapFactory::BuildServiceInstanceFor(
     content::BrowserContext* context) const {
   return new ExtensionPrefValueMap();
 }
 
 content::BrowserContext* ExtensionPrefValueMapFactory::GetBrowserContextToUse(
     content::BrowserContext* context) const {
   // Redirected in incognito.
   return extensions::ExtensionsBrowserClient::Get()->GetOriginalContext(
       context);
 }