Move Singleton and related structs to namespace base

chrome/browser/extensions/api/settings_private/settings_private_delegate_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_SETTINGS_PRIVATE_SETTINGS_PRIVATE_DELEGATE_FACTORY_H__
 #define CHROME_BROWSER_EXTENSIONS_API_SETTINGS_PRIVATE_SETTINGS_PRIVATE_DELEGATE_FACTORY_H__
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 namespace context {
 class BrowserContext;
 }
 
 namespace extensions {
 class SettingsPrivateDelegate;
 
 // BrowserContextKeyedServiceFactory for each SettingsPrivateDelegate.
 class SettingsPrivateDelegateFactory
     : public BrowserContextKeyedServiceFactory {
  public:
   static SettingsPrivateDelegate* GetForBrowserContext(
       content::BrowserContext* browser_context);
 
   static SettingsPrivateDelegateFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<SettingsPrivateDelegateFactory>;
+  friend struct base::DefaultSingletonTraits<SettingsPrivateDelegateFactory>;
 
   SettingsPrivateDelegateFactory();
   ~SettingsPrivateDelegateFactory() override;
 
   // BrowserContextKeyedBaseFactory implementation.
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
 
   DISALLOW_COPY_AND_ASSIGN(SettingsPrivateDelegateFactory);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_SETTINGS_PRIVATE_SETTINGS_PRIVATE_DELEGATE_FACTORY_H__