Created the DtlsSrtpTransport.

pc/srtptransport.h

 /*
  *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 97 matching lines @@
   // handshake.
   bool SetRtcpParams(int send_cs,
                      const uint8_t* send_key,
                      int send_key_len,
                      int recv_cs,
                      const uint8_t* recv_key,
                      int recv_key_len);
 
   void ResetParams();
 
-  // Set the header extension ids that should be encrypted for the given source.
+  // Set the header extension ids that should be encrypted.
   // This method doesn't immediately update the SRTP session with the new IDs,
   // and you need to call SetRtpParams for that to happen.
-  void SetEncryptedHeaderExtensionIds(cricket::ContentSource source,
-                                      const std::vector<int>& extension_ids);
+
+  void SetSendEncryptedHeaderExtensionIds(
+      const std::vector<int>& send_extension_ids) {
+    send_encrypted_header_extension_ids_ = send_extension_ids;
+  }
+
+  void SetRecvEncryptedHeaderExtensionIds(
+      const std::vector<int>& recv_extension_ids) {
+    recv_encrypted_header_extension_ids_ = recv_extension_ids;
+  }
 
   // If external auth is enabled, SRTP will write a dummy auth tag that then
   // later must get replaced before the packet is sent out. Only supported for
   // non-GCM cipher suites and can be checked through "IsExternalAuthActive"
   // if it is actually used. This method is only valid before the RTP params
   // have been set.
   void EnableExternalAuth();
   bool IsExternalAuthEnabled() const;
 
   // A SrtpTransport supports external creation of the auth tag if a non-GCM
@@ skipping 56 matching lines @@
   std::vector<int> send_encrypted_header_extension_ids_;
   std::vector<int> recv_encrypted_header_extension_ids_;
   bool external_auth_enabled_ = false;
 
   int rtp_abs_sendtime_extn_id_ = -1;
 };
 
 }  // namespace webrtc
 
 #endif  // PC_SRTPTRANSPORT_H_