Move Singleton and related structs to namespace base

ios/chrome/browser/enhanced_bookmarks/bookmark_server_cluster_service_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/enhanced_bookmarks/bookmark_server_cluster_service_factory.h"
 
 #include "base/logging.h"
 #include "base/memory/singleton.h"
 #include "components/enhanced_bookmarks/bookmark_server_cluster_service.h"
 #include "components/keyed_service/ios/browser_state_dependency_manager.h"
 #include "components/signin/core/browser/profile_oauth2_token_service.h"
 #include "components/signin/core/browser/signin_manager.h"
 #include "ios/chrome/browser/application_context.h"
 #include "ios/chrome/browser/browser_state/browser_state_otr_helper.h"
 #include "ios/chrome/browser/enhanced_bookmarks/enhanced_bookmark_model_factory.h"
 #include "ios/chrome/browser/signin/oauth2_token_service_factory.h"
 #include "ios/chrome/browser/signin/signin_manager_factory.h"
 #include "ios/public/provider/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/public/provider/chrome/browser/chrome_browser_provider.h"
 #include "ios/public/provider/chrome/browser/keyed_service_provider.h"
 
 namespace enhanced_bookmarks {
 
 // static
 BookmarkServerClusterServiceFactory*
 BookmarkServerClusterServiceFactory::GetInstance() {
-  return Singleton<BookmarkServerClusterServiceFactory>::get();
+  return base::Singleton<BookmarkServerClusterServiceFactory>::get();
 }
 
 // static
 BookmarkServerClusterService*
 BookmarkServerClusterServiceFactory::GetForBrowserState(
     ios::ChromeBrowserState* browser_state) {
   return static_cast<BookmarkServerClusterService*>(
       GetInstance()->GetServiceForBrowserState(browser_state, true));
 }
 
@@ skipping 27 matching lines @@
       provider->GetSyncServiceForBrowserState(browser_state),
       browser_state->GetPrefs()));
 }
 
 web::BrowserState* BookmarkServerClusterServiceFactory::GetBrowserStateToUse(
     web::BrowserState* context) const {
   return GetBrowserStateRedirectedInIncognito(context);
 }
 
 }  // namespace enhanced_bookmarks