This CL adds methods to manipulate RTP header extension, particularly

content/browser/renderer_host/p2p/socket_host.h

 // Copyright (c) 2011 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 CONTENT_BROWSER_RENDERER_HOST_P2P_SOCKET_HOST_H_
 #define CONTENT_BROWSER_RENDERER_HOST_P2P_SOCKET_HOST_H_
 
 #include "content/common/content_export.h"
 #include "content/common/p2p_socket_type.h"
 #include "net/base/ip_endpoint.h"
 #include "net/udp/datagram_socket.h"
 
 namespace IPC {
 class Sender;
 }
 
 namespace net {
 class URLRequestContextGetter;
 }
 
 namespace talk_base {
 struct PacketOptions;
 }
 
 namespace content {
 class P2PMessageThrottler;
 
+namespace packet_processing_helpers {
+
+// This method can handle only RTP packet, otherwise this method must not be
+// called. It will try to do, 1. update absolute send time extension header
+// if present with current time and 2. update HMAC in RTP packet.
+// If abs_send_time is 0, ApplyPacketOption will get current time from system.
+CONTENT_EXPORT bool ApplyPacketOptions(char* data, int length,
+                                       const talk_base::PacketOptions& options,
+                                       uint32 abs_send_time);
+
+// Helper method which finds RTP ofset and length if the packet is encapsulated
+// in a TURN Channel Message or TURN Send Indication message.
+CONTENT_EXPORT bool GetRtpPacketStartPositionAndLength(char* data, int length,
+                                                       int* rtp_start_pos,
+                                                       int* rtp_packet_length);
+// Helper method which updates absoulute send time extension if present.
+CONTENT_EXPORT bool UpdateRtpAbsSendTimeExtn(char* rtp, int length,
+                                             int extension_id,
+                                             uint32 abs_send_time);
+
+}  // packet_processing_helpers
+
 // Base class for P2P sockets.
 class CONTENT_EXPORT P2PSocketHost {
  public:
   static const int kStunHeaderSize = 20;
   // Creates P2PSocketHost of the specific type.
   static P2PSocketHost* Create(IPC::Sender* message_sender,
                                int id, P2PSocketType type,
                                net::URLRequestContextGetter* url_context,
                                P2PMessageThrottler* throttler);
 
@@ skipping 62 matching lines @@
   IPC::Sender* message_sender_;
   int id_;
   State state_;
 
   DISALLOW_COPY_AND_ASSIGN(P2PSocketHost);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_RENDERER_HOST_P2P_SOCKET_HOST_H_