This CL adds methods to manipulate RTP header extension, particularly

content/browser/renderer_host/p2p/socket_host.h

Index: content/browser/renderer_host/p2p/socket_host.h
diff --git a/content/browser/renderer_host/p2p/socket_host.h b/content/browser/renderer_host/p2p/socket_host.h
index a62401278a73aec70c6500af696f1b38d70956ee..c5bb0a7efd675adfe2ada298ed938b3a73dc8ef5 100644
--- a/content/browser/renderer_host/p2p/socket_host.h
+++ b/content/browser/renderer_host/p2p/socket_host.h
@@ -25,6 +25,24 @@ 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.
+bool MaybeUpdatePacketAbsSendTimeExtnAndRtpAuthTag(
+    char* data, int length, const talk_base::PacketOptions& options);
+
+// Helper method which finds RTP ofset and length if the packet is encapsulated
+// in a TURN Channel Message or TURN Send Indication message.
+bool GetRtpPacketStartPositionAndLength(char* data, int length,
+                                        int* rtp_start_pos,
+                                        int* rtp_packet_length);
+// Helper method which updates absoulute send time extension if present.
+bool UpdateRtpAbsSendTimeExtn(char* rtp, int length, int extension_id);
+
+}  // packet_processing_helpers
+
 // Base class for P2P sockets.
 class CONTENT_EXPORT P2PSocketHost {
  public:
@@ -53,7 +71,6 @@ class CONTENT_EXPORT P2PSocketHost {
   virtual bool SetOption(P2PSocketOption option, int value) = 0;
 
  protected:
-  friend class P2PSocketHostTcpTestBase;
 
   // TODO(mallinath) - Remove this below enum and use one defined in
   // libjingle/souce/talk/p2p/base/stun.h