Move Singleton and related structs to namespace base

chrome/browser/domain_reliability/service_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_DOMAIN_RELIABILITY_SERVICE_FACTORY_H_
 #define CHROME_BROWSER_DOMAIN_RELIABILITY_SERVICE_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 namespace content {
 class BrowserContext;
 }  // namespace content
 
 namespace domain_reliability {
 
 class DomainReliabilityService;
 
 // Creates DomainReliabilityServices for BrowserContexts. Initializes them with
 // the hardcoded upload reporter string "chrome".
 class DomainReliabilityServiceFactory
     : public BrowserContextKeyedServiceFactory {
  public:
   static DomainReliabilityService* GetForBrowserContext(
       content::BrowserContext* context);
 
   static DomainReliabilityServiceFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<DomainReliabilityServiceFactory>;
+  friend struct base::DefaultSingletonTraits<DomainReliabilityServiceFactory>;
 
   DomainReliabilityServiceFactory();
   ~DomainReliabilityServiceFactory() override;
 
   // BrowserContextKeyedServiceFactory implementation:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
 
   DISALLOW_COPY_AND_ASSIGN(DomainReliabilityServiceFactory);
 };
 
 }  // namespace domain_reliability
 
 #endif  // CHROME_BROWSER_DOMAIN_RELIABILITY_SERVICE_FACTORY_H_