Move Singleton and related structs to namespace base

chrome/browser/apps/shortcut_manager_factory.h

 // Copyright 2013 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 CHROME_BROWSER_APPS_SHORTCUT_MANAGER_FACTORY_H_
 #define CHROME_BROWSER_APPS_SHORTCUT_MANAGER_FACTORY_H_
 
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
+namespace base {
 template<typename Type> struct DefaultSingletonTraits;
+}
 
 class Profile;
 
 class AppShortcutManager;
 
 // Singleton that owns all AppShortcutManagers and associates them with
 // Profiles. Listens for the Profile's destruction notification and cleans up
 // the associated AppShortcutManager.
 // AppShortcutManagers should not exist in incognito profiles.
 class AppShortcutManagerFactory : public BrowserContextKeyedServiceFactory {
  public:
   static AppShortcutManager* GetForProfile(Profile* profile);
 
   static AppShortcutManagerFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<AppShortcutManagerFactory>;
+  friend struct base::DefaultSingletonTraits<AppShortcutManagerFactory>;
 
   AppShortcutManagerFactory();
   ~AppShortcutManagerFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   bool ServiceIsNULLWhileTesting() const override;
 };
 
 #endif  // CHROME_BROWSER_APPS_SHORTCUT_MANAGER_FACTORY_H_