Move Singleton and related structs to namespace base

chrome/browser/ui/gesture_prefs_observer_factory_aura.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_GESTURE_PREFS_OBSERVER_FACTORY_AURA_H_
 #define CHROME_BROWSER_UI_GESTURE_PREFS_OBSERVER_FACTORY_AURA_H_
 
 #include "base/basictypes.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 class PrefService;
 class Profile;
 
 // Create an observer per Profile that listens for gesture preferences updates.
 class GesturePrefsObserverFactoryAura
     : public BrowserContextKeyedServiceFactory {
  public:
   static GesturePrefsObserverFactoryAura* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<GesturePrefsObserverFactoryAura>;
+  friend struct base::DefaultSingletonTraits<GesturePrefsObserverFactoryAura>;
 
   GesturePrefsObserverFactoryAura();
   ~GesturePrefsObserverFactoryAura() override;
 
   void RegisterOverscrollPrefs(user_prefs::PrefRegistrySyncable* registry);
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* profile) const override;
   void RegisterProfilePrefs(
       user_prefs::PrefRegistrySyncable* registry) override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   content::BrowserContext* GetBrowserContextToUse(
       content::BrowserContext* context) const override;
   bool ServiceIsNULLWhileTesting() const override;
 
   DISALLOW_COPY_AND_ASSIGN(GesturePrefsObserverFactoryAura);
 };
 
 #endif  // CHROME_BROWSER_UI_GESTURE_PREFS_OBSERVER_FACTORY_AURA_H_