Remove the dependency of TransportChannel and TransportChannelImpl.

webrtc/media/sctp/sctptransport.h

Index: webrtc/media/sctp/sctptransport.h
diff --git a/webrtc/media/sctp/sctptransport.h b/webrtc/media/sctp/sctptransport.h
index 6d3a41a8f16092be6b9e0b9179821b286b4fd944..d501e3499ffc52c006cd6a417d672f06444979b4 100644
--- a/webrtc/media/sctp/sctptransport.h
+++ b/webrtc/media/sctp/sctptransport.h
@@ -26,7 +26,6 @@
 // For SendDataParams/ReceiveDataParams.
 #include "webrtc/media/base/mediachannel.h"
 #include "webrtc/media/sctp/sctptransportinternal.h"
-#include "webrtc/p2p/base/transportchannel.h"
 
 // Defined by "usrsctplib/usrsctp.h"
 struct sockaddr_conn;
@@ -67,11 +66,11 @@ class SctpTransport : public SctpTransportInternal,
   // methods can be called.
   // |channel| is required (must not be null).
   SctpTransport(rtc::Thread* network_thread,
-                cricket::TransportChannel* channel);
+                cricket::DtlsTransportInternal* channel);

[pthatcher1, 2017/01/17 20:16:48]

Can SctpTransport take just a PacketTransportInterface?  I don't see why it
needs anything DTLS specific.

   ~SctpTransport() override;
 
   // SctpTransportInternal overrides (see sctptransportinternal.h for comments).
-  void SetTransportChannel(cricket::TransportChannel* channel) override;
+  void SetTransportChannel(cricket::DtlsTransportInternal* channel) override;
   bool Start(int local_port, int remote_port) override;
   bool OpenStream(int sid) override;
   bool ResetStream(int sid) override;
@@ -140,7 +139,7 @@ class SctpTransport : public SctpTransportInternal,
   // Helps pass inbound/outbound packets asynchronously to the network thread.
   rtc::AsyncInvoker invoker_;
   // Underlying DTLS channel.
-  TransportChannel* transport_channel_;
+  DtlsTransportInternal* transport_channel_;

[pthatcher1, 2017/01/17 20:16:48]

This file could use some channel => transport renaming, but I'm OK with you
leaving a TODO and doing it in a separate CL.

   bool was_ever_writable_ = false;
   int local_port_ = kSctpDefaultPort;
   int remote_port_ = kSctpDefaultPort;
@@ -179,7 +178,7 @@ class SctpTransportFactory : public SctpTransportInternalFactory {
       : network_thread_(network_thread) {}
 
   std::unique_ptr<SctpTransportInternal> CreateSctpTransport(
-      TransportChannel* channel) override {
+      DtlsTransportInternal* channel) override {
     return std::unique_ptr<SctpTransportInternal>(
         new SctpTransport(network_thread_, channel));
   }