Move Singleton and related structs to namespace base

chrome/browser/media/midi_permission_context_factory.cc

 // 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 "chrome/browser/media/midi_permission_context_factory.h"
 
 #include "chrome/browser/media/midi_permission_context.h"
 #include "chrome/browser/profiles/incognito_helpers.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 
 // static
 MidiPermissionContext*
 MidiPermissionContextFactory::GetForProfile(Profile* profile) {
   return static_cast<MidiPermissionContext*>(
       GetInstance()->GetServiceForBrowserContext(profile, true));
 }
 
 // static
 MidiPermissionContextFactory*
 MidiPermissionContextFactory::GetInstance() {
-  return Singleton<MidiPermissionContextFactory>::get();
+  return base::Singleton<MidiPermissionContextFactory>::get();
 }
 
 MidiPermissionContextFactory::MidiPermissionContextFactory()
     : BrowserContextKeyedServiceFactory(
           "MidiPermissionContext",
           BrowserContextDependencyManager::GetInstance()) {
 }
 
 MidiPermissionContextFactory::~MidiPermissionContextFactory() {
 }
 
 KeyedService* MidiPermissionContextFactory::BuildServiceInstanceFor(
     content::BrowserContext* profile) const {
   return new MidiPermissionContext(static_cast<Profile*>(profile));
 }
 
 content::BrowserContext*
 MidiPermissionContextFactory::GetBrowserContextToUse(
     content::BrowserContext* context) const {
   return chrome::GetBrowserContextOwnInstanceInIncognito(context);
 }