First step to remove SingleRequestHostResolver.

net/socket/socks_client_socket.h

Index: net/socket/socks_client_socket.h
diff --git a/net/socket/socks_client_socket.h b/net/socket/socks_client_socket.h
index d6702631c998ab9118c2f213e984dfd3c6ae5426..1d55784e03d07168182df098c2f35b1408f30230 100644
--- a/net/socket/socks_client_socket.h
+++ b/net/socket/socks_client_socket.h
@@ -18,7 +18,6 @@
 #include "net/base/completion_callback.h"
 #include "net/base/net_errors.h"
 #include "net/dns/host_resolver.h"
-#include "net/dns/single_request_host_resolver.h"
 #include "net/log/net_log.h"
 #include "net/socket/stream_socket.h"
 
@@ -131,7 +130,8 @@ class NET_EXPORT_PRIVATE SOCKSClientSocket : public StreamSocket {
   bool was_ever_used_;
 
   // Used to resolve the hostname to which the SOCKS proxy will connect.
-  SingleRequestHostResolver host_resolver_;
+  HostResolver* host_resolver_;
+  std::unique_ptr<HostResolver::Request> request_;
   AddressList addresses_;
   HostResolver::RequestInfo host_request_info_;
   RequestPriority priority_;