Move Singleton and related structs to namespace base

chrome/browser/predictors/resource_prefetch_predictor_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 CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_FACTORY_H_
 #define CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_FACTORY_H_
 
 #include "base/basictypes.h"
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 namespace predictors {
 
 class ResourcePrefetchPredictor;
 
 class ResourcePrefetchPredictorFactory
     : public BrowserContextKeyedServiceFactory {
  public:
   static ResourcePrefetchPredictor* GetForProfile(
       content::BrowserContext* context);
   static ResourcePrefetchPredictorFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<ResourcePrefetchPredictorFactory>;
+  friend struct base::DefaultSingletonTraits<ResourcePrefetchPredictorFactory>;
 
   ResourcePrefetchPredictorFactory();
   ~ResourcePrefetchPredictorFactory() override;
 
   // RefcountedBrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
 
   DISALLOW_COPY_AND_ASSIGN(ResourcePrefetchPredictorFactory);
 };
 
 }  // namespace predictors
 
 #endif  // CHROME_BROWSER_PREDICTORS_RESOURCE_PREFETCH_PREDICTOR_FACTORY_H_