This CL adds methods to manipulate RTP header extension, particularly

content/browser/renderer_host/p2p/socket_host_udp.cc

 // 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.
 
 #include "content/browser/renderer_host/p2p/socket_host_udp.h"
 
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/debug/trace_event.h"
 #include "base/stl_util.h"
@@ skipping 216 matching lines @@
     int result = socket_->SetDiffServCodePoint(packet.dscp);
     if (result == net::OK) {
       last_dscp_ = packet.dscp;
     } else if (!IsTransientError(result) && last_dscp_ != net::DSCP_CS0) {
       // We receieved a non-transient error, and it seems we have
       // not changed the DSCP in the past, disable DSCP as it unlikely
       // to work in the future.
       last_dscp_ = net::DSCP_NO_CHANGE;
     }
   }
+  MaybeUpdateRtpSendTimeExtn(packet.data->data(), packet.size);
   int result = socket_->SendTo(
       packet.data.get(),
       packet.size,
       packet.to,
       base::Bind(&P2PSocketHostUdp::OnSend, base::Unretained(this), packet.id));
 
   // sendto() may return an error, e.g. if we've received an ICMP Destination
   // Unreachable message. When this happens try sending the same packet again,
   // and just drop it if it fails again.
   if (IsTransientError(result)) {
@@ skipping 58 matching lines @@
     case P2P_SOCKET_OPT_DSCP:
       return (net::OK == socket_->SetDiffServCodePoint(
           static_cast<net::DiffServCodePoint>(value))) ? true : false;
     default:
       NOTREACHED();
       return false;
   }
 }
 
 }  // namespace content