Move Singleton and related structs to namespace base

chrome/browser/ui/tabs/pinned_tab_service_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 CHROME_BROWSER_UI_TABS_PINNED_TAB_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_UI_TABS_PINNED_TAB_SERVICE_FACTORY_H_
 
 #include "base/compiler_specific.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 class PinnedTabService;
 class Profile;
 
 // Singleton that owns all PinnedTabServices and associates them with Profiles.
 // Listens for the Profile's destruction notification and cleans up the
 // associated PinnedTabService.
 class PinnedTabServiceFactory : public BrowserContextKeyedServiceFactory {
  public:
   // Returns the PinnedTabService that tracks pinning changes for |profile|.
   static PinnedTabService* GetForProfile(Profile* profile);
 
   static PinnedTabServiceFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<PinnedTabServiceFactory>;
+  friend struct base::DefaultSingletonTraits<PinnedTabServiceFactory>;
 
   PinnedTabServiceFactory();
   ~PinnedTabServiceFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   bool ServiceIsNULLWhileTesting() const override;
 };
 
 #endif  // CHROME_BROWSER_UI_TABS_PINNED_TAB_SERVICE_FACTORY_H_