Remove the dependency of TransportChannel and TransportChannelImpl.

webrtc/api/webrtcsession.cc

Index: webrtc/api/webrtcsession.cc
diff --git a/webrtc/api/webrtcsession.cc b/webrtc/api/webrtcsession.cc
index 94ebc07f059151b1163a48f44cf7d02a1506b35c..4ad7ad52a5fe194edd3ed56b4f0b8c351aac31a7 100644
--- a/webrtc/api/webrtcsession.cc
+++ b/webrtc/api/webrtcsession.cc
@@ -35,7 +35,6 @@
 #include "webrtc/media/base/videocapturer.h"
 #include "webrtc/media/sctp/sctptransportinternal.h"
 #include "webrtc/p2p/base/portallocator.h"
-#include "webrtc/p2p/base/transportchannel.h"
 #include "webrtc/pc/channel.h"
 #include "webrtc/pc/channelmanager.h"
 #include "webrtc/pc/mediasession.h"
@@ -1896,7 +1895,7 @@ bool WebRtcSession::CreateSctpTransport_n(const std::string& content_name,
                                           const std::string& transport_name) {
   RTC_DCHECK(network_thread_->IsCurrent());
   RTC_DCHECK(sctp_factory_);
-  cricket::TransportChannel* tc =
+  cricket::DtlsTransportInternal* tc =
       transport_controller_->CreateTransportChannel_n(
           transport_name, cricket::ICE_CANDIDATE_COMPONENT_RTP);
   sctp_transport_ = sctp_factory_->CreateSctpTransport(tc);
@@ -1919,7 +1918,7 @@ void WebRtcSession::ChangeSctpTransport_n(const std::string& transport_name) {
   RTC_DCHECK(sctp_transport_name_);
   std::string old_sctp_transport_name = *sctp_transport_name_;
   sctp_transport_name_ = rtc::Optional<std::string>(transport_name);
-  cricket::TransportChannel* tc =
+  cricket::DtlsTransportInternal* tc =
       transport_controller_->CreateTransportChannel_n(
           transport_name, cricket::ICE_CANDIDATE_COMPONENT_RTP);

[pthatcher1, 2017/01/13 22:41:16]

If it returns a DtlsTransport, then we should rename the TransportController to
be CreateDtlsTransport.

[Zhi Huang, 2017/01/16 10:38:24]

Sure. There will be no concept of "channel" in P2P level. 
Done

   sctp_transport_->SetTransportChannel(tc);