Revert of Remove GetTransport() from TransportChannelImpl

webrtc/p2p/base/transportchannelimpl.h

Index: webrtc/p2p/base/transportchannelimpl.h
diff --git a/webrtc/p2p/base/transportchannelimpl.h b/webrtc/p2p/base/transportchannelimpl.h
index 1fa088a30dd928658b26685e3d0b97d0f960e41e..8d4d4bb728ebaad3582452a8f37c1b0fbf9824b0 100644
--- a/webrtc/p2p/base/transportchannelimpl.h
+++ b/webrtc/p2p/base/transportchannelimpl.h
@@ -12,6 +12,7 @@
 #define WEBRTC_P2P_BASE_TRANSPORTCHANNELIMPL_H_
 
 #include <string>
+#include "webrtc/p2p/base/transport.h"
 #include "webrtc/p2p/base/transportchannel.h"
 
 namespace buzz { class XmlElement; }
@@ -34,6 +35,9 @@
   explicit TransportChannelImpl(const std::string& transport_name,
                                 int component)
       : TransportChannel(transport_name, component) {}
+
+  // Returns the transport that created this channel.
+  virtual Transport* GetTransport() = 0;
 
   // For ICE channels.
   virtual IceRole GetIceRole() const = 0;