First step to remove SingleRequestHostResolver.

net/socket/transport_client_socket_pool.h

 // Copyright (c) 2012 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.
 
 #ifndef NET_SOCKET_TRANSPORT_CLIENT_SOCKET_POOL_H_
 #define NET_SOCKET_TRANSPORT_CLIENT_SOCKET_POOL_H_
 
 #include <memory>
 #include <string>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "net/base/host_port_pair.h"
 #include "net/dns/host_resolver.h"
-#include "net/dns/single_request_host_resolver.h"
 #include "net/socket/client_socket_pool.h"
 #include "net/socket/client_socket_pool_base.h"
 #include "net/socket/connection_attempts.h"
 
 namespace net {
 
 class ClientSocketFactory;
 class SocketPerformanceWatcherFactory;
 
 typedef base::Callback<int(const AddressList&, const BoundNetLog& net_log)>
@@ skipping 129 matching lines @@
   void DoIPv6FallbackTransportConnectComplete(int result);
 
   // Begins the host resolution and the TCP connect.  Returns OK on success
   // and ERR_IO_PENDING if it cannot immediately service the request.
   // Otherwise, it returns a net error code.
   int ConnectInternal() override;
 
   void CopyConnectionAttemptsFromSockets();
 
   scoped_refptr<TransportSocketParams> params_;
-  SingleRequestHostResolver resolver_;
+  HostResolver* resolver_;
+  std::unique_ptr<HostResolver::Request> request_;
   ClientSocketFactory* const client_socket_factory_;
 
   State next_state_;
 
   std::unique_ptr<StreamSocket> transport_socket_;
   AddressList addresses_;
 
   std::unique_ptr<StreamSocket> fallback_transport_socket_;
   std::unique_ptr<AddressList> fallback_addresses_;
   base::TimeTicks fallback_connect_start_time_;
@@ skipping 108 matching lines @@
   };
 
   PoolBase base_;
 
   DISALLOW_COPY_AND_ASSIGN(TransportClientSocketPool);
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_TRANSPORT_CLIENT_SOCKET_POOL_H_