Move Singleton and related structs to namespace base

chrome/browser/extensions/api/search_engines_private/search_engines_private_event_router_factory.h

 // Copyright 2015 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_EXTENSIONS_API_SEARCH_ENGINES_PRIVATE_SEARCH_ENGINES_PRIVATE_EVENT_ROUTER_FACTORY_H_
 #define CHROME_BROWSER_EXTENSIONS_API_SEARCH_ENGINES_PRIVATE_SEARCH_ENGINES_PRIVATE_EVENT_ROUTER_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
@@ skipping 16 matching lines @@
   static SearchEnginesPrivateEventRouterFactory* GetInstance();
 
  protected:
   // BrowserContextKeyedBaseFactory overrides:
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   bool ServiceIsNULLWhileTesting() const override;
 
  private:
-  friend struct DefaultSingletonTraits<SearchEnginesPrivateEventRouterFactory>;
+  friend struct base::DefaultSingletonTraits<
+      SearchEnginesPrivateEventRouterFactory>;
 
   SearchEnginesPrivateEventRouterFactory();
   ~SearchEnginesPrivateEventRouterFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
 
   DISALLOW_COPY_AND_ASSIGN(SearchEnginesPrivateEventRouterFactory);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_SEARCH_ENGINES_PRIVATE_SEARCH_ENGINES_PRIVATE_EVENT_ROUTER_FACTORY_H_