Move Singleton and related structs to namespace base

chrome/browser/dom_distiller/dom_distiller_service_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_DOM_DISTILLER_DOM_DISTILLER_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_DOM_DISTILLER_DOM_DISTILLER_SERVICE_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/dom_distiller/core/distilled_page_prefs.h"
 #include "components/dom_distiller/core/dom_distiller_service.h"
@@ skipping 22 matching lines @@
   DISALLOW_COPY_AND_ASSIGN(DomDistillerContextKeyedService);
 };
 
 class DomDistillerServiceFactory : public BrowserContextKeyedServiceFactory {
  public:
   static DomDistillerServiceFactory* GetInstance();
   static DomDistillerContextKeyedService* GetForBrowserContext(
       content::BrowserContext* context);
 
  private:
-  friend struct DefaultSingletonTraits<DomDistillerServiceFactory>;
+  friend struct base::DefaultSingletonTraits<DomDistillerServiceFactory>;
 
   DomDistillerServiceFactory();
   ~DomDistillerServiceFactory() override;
 
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
 
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
 };
 
 }  // namespace dom_distiller
 
 #endif  // CHROME_BROWSER_DOM_DISTILLER_DOM_DISTILLER_SERVICE_FACTORY_H_