Remove the dependency of TransportChannel and TransportChannelImpl.

webrtc/p2p/base/dtlstransportinternal.h

Index: webrtc/p2p/base/dtlstransportinternal.h
diff --git a/webrtc/p2p/base/dtlstransportinternal.h b/webrtc/p2p/base/dtlstransportinternal.h
index 780c128e0068fbc2b7c3ceb48a395bc268c054dc..363ad601d2f64a2a7d961229371fe8d4dbeb8137 100644
--- a/webrtc/p2p/base/dtlstransportinternal.h
+++ b/webrtc/p2p/base/dtlstransportinternal.h
@@ -22,6 +22,12 @@
 
 namespace cricket {
 
+enum PacketFlags {
+  PF_NORMAL = 0x00,       // A normal packet.
+  PF_SRTP_BYPASS = 0x01,  // An encrypted SRTP packet; bypass any additional
+                          // crypto provided by the transport (e.g. DTLS)
+};
+
 // DtlsTransportInternal is an internal interface that does DTLS.
 // Once the public interface is supported,
 // (https://www.w3.org/TR/webrtc/#rtcdtlstransport-interface)
@@ -90,10 +96,13 @@ class DtlsTransportInternal : public rtc::PacketTransportInterface {
   sigslot::signal1<rtc::SSLHandshakeError> SignalDtlsHandshakeError;
 
   // Debugging description of this transport.
-  std::string debug_name() const override {
+  const std::string debug_name() const override {

[Taylor Brandstetter, 2017/01/10 19:43:47]

Like I mentioned earlier, we can remove the "const" from the return value.

[Zhi Huang, 2017/01/12 20:04:12]

Done.

     return transport_name() + " " + std::to_string(component());
   }
 
+ protected:
+  DtlsTransportInternal() {}
+
  private:
   RTC_DISALLOW_COPY_AND_ASSIGN(DtlsTransportInternal);
 };