Move Singleton and related structs to namespace base

extensions/browser/api/idle/idle_manager_factory.h

 // Copyright (c) 2012 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.
 
 #ifndef EXTENSIONS_BROWSER_API_IDLE_IDLE_MANAGER_FACTORY_H__
 #define EXTENSIONS_BROWSER_API_IDLE_IDLE_MANAGER_FACTORY_H__
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 namespace content {
 class BrowserContext;
 }  // namespace content
 
 namespace extensions {
 class IdleManager;
 
 class IdleManagerFactory : public BrowserContextKeyedServiceFactory {
  public:
   static IdleManager* GetForBrowserContext(content::BrowserContext* context);
 
   static IdleManagerFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<IdleManagerFactory>;
+  friend struct base::DefaultSingletonTraits<IdleManagerFactory>;
 
   IdleManagerFactory();
   ~IdleManagerFactory() override;
 
   // BrowserContextKeyedBaseFactory implementation.
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   bool ServiceIsNULLWhileTesting() const override;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_API_IDLE_IDLE_MANAGER_FACTORY_H__