Move Singleton and related structs to namespace base

chrome/browser/apps/per_app_settings_service_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 "chrome/browser/apps/per_app_settings_service_factory.h"
 
 #include "base/memory/singleton.h"
 #include "chrome/browser/apps/per_app_settings_service.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "extensions/browser/extensions_browser_client.h"
 
 // static
 PerAppSettingsServiceFactory* PerAppSettingsServiceFactory::GetInstance() {
-  return Singleton<PerAppSettingsServiceFactory>::get();
+  return base::Singleton<PerAppSettingsServiceFactory>::get();
 }
 
 // static
 PerAppSettingsService* PerAppSettingsServiceFactory::GetForBrowserContext(
     content::BrowserContext* browser_context) {
   return static_cast<PerAppSettingsService*>(
       GetInstance()->GetServiceForBrowserContext(
           browser_context, true /* create */));
 }
 
@@ skipping 12 matching lines @@
 
 bool PerAppSettingsServiceFactory::ServiceIsCreatedWithBrowserContext() const {
   return false;
 }
 
 content::BrowserContext* PerAppSettingsServiceFactory::GetBrowserContextToUse(
     content::BrowserContext* context) const {
   return extensions::ExtensionsBrowserClient::Get()->
       GetOriginalContext(context);
 }