Add UMA for the kernel's TCP RTT estimate.

net/socket/tcp_socket_win.cc

 // Copyright 2013 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/socket/tcp_socket.h"
 #include "net/socket/tcp_socket_win.h"
 
 #include <mstcpip.h>
 
 #include "base/callback_helpers.h"
@@ skipping 1025 matching lines @@
   }
 
   waiting_read_ = false;
   core_->read_iobuffer_ = NULL;
   core_->read_buffer_length_ = 0;
 
   DCHECK_NE(rv, ERR_IO_PENDING);
   base::ResetAndReturn(&read_callback_).Run(rv);
 }
 
+bool TCPSocketWin::GetEstimatedRoundTripTime(base::TimeDelta* out_rtt) {
+  DCHECK(out_rtt);
+  // Not implemented. Consider implementing using
+  // GetPerTcpConnectionEStats/GetPerTcp6ConnectionEStats.
+  return false;
+}
+
 }  // namespace net