Move Singleton and related structs to namespace base

ios/web/webui/web_ui_ios_controller_factory_registry.cc

 // 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.
 
 #include "ios/web/webui/web_ui_ios_controller_factory_registry.h"
 
 #include "base/lazy_instance.h"
 #include "url/gurl.h"
 #include "url/url_constants.h"
 
 namespace web {
 
 base::LazyInstance<std::vector<WebUIIOSControllerFactory*> > g_factories =
     LAZY_INSTANCE_INITIALIZER;
 
 void WebUIIOSControllerFactory::RegisterFactory(
     WebUIIOSControllerFactory* factory) {
   g_factories.Pointer()->push_back(factory);
 }
 
 WebUIIOSControllerFactoryRegistry*
 WebUIIOSControllerFactoryRegistry::GetInstance() {
-  return Singleton<WebUIIOSControllerFactoryRegistry>::get();
+  return base::Singleton<WebUIIOSControllerFactoryRegistry>::get();
 }
 
 WebUIIOSController*
 WebUIIOSControllerFactoryRegistry::CreateWebUIIOSControllerForURL(
     WebUIIOS* web_ui,
     const GURL& url) const {
   std::vector<WebUIIOSControllerFactory*>* factories = g_factories.Pointer();
   for (size_t i = 0; i < factories->size(); ++i) {
     WebUIIOSController* controller =
         (*factories)[i]->CreateWebUIIOSControllerForURL(web_ui, url);
     if (controller)
       return controller;
   }
   return NULL;
 }
 
 WebUIIOSControllerFactoryRegistry::WebUIIOSControllerFactoryRegistry() {
 }
 
 WebUIIOSControllerFactoryRegistry::~WebUIIOSControllerFactoryRegistry() {
 }
 
 }  // namespace web