Move Singleton and related structs to namespace base

extensions/browser/image_loader_factory.h

 // 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.
 
 #ifndef EXTENSIONS_BROWSER_IMAGE_LOADER_FACTORY_H_
 #define EXTENSIONS_BROWSER_IMAGE_LOADER_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 namespace content {
 class BrowserContext;
 }
 
 namespace extensions {
 
 class ImageLoader;
 
 // Singleton that owns all ImageLoaders and associates them with
 // BrowserContexts. Listens for the BrowserContext's destruction notification
 // and cleans up the associated ImageLoader. Uses the original BrowserContext
 // for incognito contexts.
 class ImageLoaderFactory : public BrowserContextKeyedServiceFactory {
  public:
   static ImageLoader* GetForBrowserContext(content::BrowserContext* context);
 
   static ImageLoaderFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<ImageLoaderFactory>;
+  friend struct base::DefaultSingletonTraits<ImageLoaderFactory>;
 
   ImageLoaderFactory();
   ~ImageLoaderFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_IMAGE_LOADER_FACTORY_H_