Move Singleton and related structs to namespace base

extensions/browser/event_router_factory.cc

 // Copyright 2015 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 "extensions/browser/event_router_factory.h"
 
 #include "components/keyed_service/content/browser_context_dependency_manager.h"
 #include "content/public/browser/browser_context.h"
 #include "extensions/browser/event_router.h"
 #include "extensions/browser/extension_prefs.h"
 #include "extensions/browser/extension_prefs_factory.h"
 #include "extensions/browser/extension_registry_factory.h"
 #include "extensions/browser/extensions_browser_client.h"
 
 using content::BrowserContext;
 
 namespace extensions {
 
 // static
 EventRouter* EventRouterFactory::GetForBrowserContext(BrowserContext* context) {
   return static_cast<EventRouter*>(
       GetInstance()->GetServiceForBrowserContext(context, true));
 }
 
 // static
 EventRouterFactory* EventRouterFactory::GetInstance() {
-  return Singleton<EventRouterFactory>::get();
+  return base::Singleton<EventRouterFactory>::get();
 }
 
 EventRouterFactory::EventRouterFactory()
     : BrowserContextKeyedServiceFactory(
           "EventRouter",
           BrowserContextDependencyManager::GetInstance()) {
   DependsOn(ExtensionRegistryFactory::GetInstance());
   DependsOn(ExtensionPrefsFactory::GetInstance());
 }
 
 EventRouterFactory::~EventRouterFactory() {
 }
 
 KeyedService* EventRouterFactory::BuildServiceInstanceFor(
     BrowserContext* context) const {
   return new EventRouter(context, ExtensionPrefs::Get(context));
 }
 
 BrowserContext* EventRouterFactory::GetBrowserContextToUse(
     BrowserContext* context) const {
   // Redirected in incognito.
   return ExtensionsBrowserClient::Get()->GetOriginalContext(context);
 }
 
 }  // namespace extensions