Move Singleton and related structs to namespace base

chrome/browser/policy/cloud/user_cloud_policy_invalidator_factory.h

 // Copyright 2013 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_POLICY_CLOUD_USER_CLOUD_POLICY_INVALIDATOR_FACTORY_H_
 #define CHROME_BROWSER_POLICY_CLOUD_USER_CLOUD_POLICY_INVALIDATOR_FACTORY_H_
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 namespace policy {
 
 // Creates an instance of UserCloudPolicyInvalidator for each profile.
 class UserCloudPolicyInvalidatorFactory
     : public BrowserContextKeyedServiceFactory {
  public:
   static UserCloudPolicyInvalidatorFactory* GetInstance();
 
  private:
-  friend struct DefaultSingletonTraits<UserCloudPolicyInvalidatorFactory>;
+  friend struct base::DefaultSingletonTraits<UserCloudPolicyInvalidatorFactory>;
 
   UserCloudPolicyInvalidatorFactory();
   ~UserCloudPolicyInvalidatorFactory() override;
 
   // BrowserContextKeyedServiceFactory:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   bool ServiceIsNULLWhileTesting() const override;
 
   DISALLOW_COPY_AND_ASSIGN(UserCloudPolicyInvalidatorFactory);
 };
 
 }  // namespace policy
 
 #endif  // CHROME_BROWSER_POLICY_CLOUD_USER_CLOUD_POLICY_INVALIDATOR_FACTORY_H_