Avoid doing concurrent DNS resolves of the same hostname

net/ftp/ftp_network_layer.cc

 // Copyright (c) 2008 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 "net/ftp/ftp_network_layer.h"
 
 #include "net/base/client_socket_factory.h"
 #include "net/ftp/ftp_network_session.h"
 #include "net/ftp/ftp_network_transaction.h"
 
 namespace net {
 
-FtpNetworkLayer::FtpNetworkLayer()
-    : suspended_(false) {
-  session_ = new FtpNetworkSession();
+FtpNetworkLayer::FtpNetworkLayer(HostResolver* host_resolver)
+    : session_(new FtpNetworkSession(host_resolver)),
+      suspended_(false) {
 }
 
 FtpNetworkLayer::~FtpNetworkLayer() {
 }
 
 // static
-FtpTransactionFactory* FtpNetworkLayer::CreateFactory() {
-  return new FtpNetworkLayer();
+FtpTransactionFactory* FtpNetworkLayer::CreateFactory(
+    HostResolver* host_resolver) {
+  return new FtpNetworkLayer(host_resolver);
 }
 
 FtpTransaction* FtpNetworkLayer::CreateTransaction() {
   if (suspended_)
     return NULL;
 
   return new FtpNetworkTransaction(
       session_, ClientSocketFactory::GetDefaultFactory());
 }
 
 void FtpNetworkLayer::Suspend(bool suspend) {
   suspended_ = suspend;
 
   /* TODO(darin): We'll need this code once we have a connection manager.
   if (suspend)
     session_->connection_manager()->CloseIdleSockets();
   */
 }
 
 }  // namespace net