Move Singleton and related structs to namespace base

chrome/browser/chromeos/file_manager/volume_manager_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.
 
 #include "base/basictypes.h"
 #include "components/keyed_service/content/browser_context_keyed_service_factory.h"
 
 #ifndef CHROME_BROWSER_CHROMEOS_FILE_MANAGER_VOLUME_MANAGER_FACTORY_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_MANAGER_VOLUME_MANAGER_FACTORY_H_
 
-template<typename T> struct DefaultSingletonTraits;
+namespace base {
+template <typename T>
+struct DefaultSingletonTraits;
+}  // namespace base
 
 namespace content {
 class BrowserContext;
 }  // namespace content
 
 namespace file_manager {
 
 class VolumeManager;
 
 // Factory to create VolumeManager.
@@ skipping 10 matching lines @@
       content::BrowserContext* context) const override;
   bool ServiceIsCreatedWithBrowserContext() const override;
   bool ServiceIsNULLWhileTesting() const override;
 
   // BrowserContextKeyedServiceFactory overrides:
   KeyedService* BuildServiceInstanceFor(
       content::BrowserContext* context) const override;
 
  private:
   // For Singleton.
-  friend struct DefaultSingletonTraits<VolumeManagerFactory>;
+  friend struct base::DefaultSingletonTraits<VolumeManagerFactory>;
 
   VolumeManagerFactory();
   ~VolumeManagerFactory() override;
 
   DISALLOW_COPY_AND_ASSIGN(VolumeManagerFactory);
 };
 
 }  // namespace file_manager
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_MANAGER_VOLUME_MANAGER_FACTORY_H_