Move Singleton and related structs to namespace base

ios/chrome/browser/bookmarks/bookmark_client_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 "ios/chrome/browser/bookmarks/bookmark_client_factory.h"
 
 #include "base/memory/singleton.h"
 #include "components/keyed_service/core/service_access_type.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "ios/chrome/browser/bookmarks/bookmark_client_impl.h"
@@ skipping 16 matching lines @@
 
 // static
 BookmarkClientImpl* BookmarkClientFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return static_cast<BookmarkClientImpl*>(
       GetInstance()->GetServiceForBrowserState(browser_state, true));
 }
 
 // static
 BookmarkClientFactory* BookmarkClientFactory::GetInstance() {
-  return Singleton<BookmarkClientFactory>::get();
+  return base::Singleton<BookmarkClientFactory>::get();
 }
 
 // static
 BrowserStateKeyedServiceFactory::TestingFactoryFunction
 BookmarkClientFactory::GetDefaultFactory() {
   return &BuildBookmarkClientImpl;
 }
 
 BookmarkClientFactory::BookmarkClientFactory()
     : BrowserStateKeyedServiceFactory(
@@ skipping 10 matching lines @@
 }
 
 web::BrowserState* BookmarkClientFactory::GetBrowserStateToUse(
     web::BrowserState* context) const {
   return GetBrowserStateRedirectedInIncognito(context);
 }
 
 bool BookmarkClientFactory::ServiceIsNULLWhileTesting() const {
   return true;
 }