Created the DtlsSrtpTransport.

pc/srtptransport.cc

 /*
  *  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 235 matching lines @@
 }
 
 void SrtpTransport::ResetParams() {
   send_session_ = nullptr;
   recv_session_ = nullptr;
   send_rtcp_session_ = nullptr;
   recv_rtcp_session_ = nullptr;
   LOG(LS_INFO) << "The params in SRTP transport are reset.";
 }
 
-void SrtpTransport::SetEncryptedHeaderExtensionIds(
-    cricket::ContentSource source,
-    const std::vector<int>& extension_ids) {
-  if (source == cricket::CS_LOCAL) {
-    recv_encrypted_header_extension_ids_ = extension_ids;
-  } else {
-    send_encrypted_header_extension_ids_ = extension_ids;
-  }
-}
-
 void SrtpTransport::CreateSrtpSessions() {
   send_session_.reset(new cricket::SrtpSession());
   recv_session_.reset(new cricket::SrtpSession());
 
   if (external_auth_enabled_) {
     send_session_->EnableExternalAuth();
   }
 }
 
 bool SrtpTransport::ProtectRtp(void* p, int in_len, int max_len, int* out_len) {
@@ skipping 92 matching lines @@
   if (!IsActive()) {
     LOG(LS_WARNING) << "Failed to check IsExternalAuthActive: SRTP not active";
     return false;
   }
 
   RTC_CHECK(send_session_);
   return send_session_->IsExternalAuthActive();
 }
 
 }  // namespace webrtc