Remove the dependency of TransportChannel and TransportChannelImpl.

webrtc/p2p/base/transportcontroller.h

Index: webrtc/p2p/base/transportcontroller.h
diff --git a/webrtc/p2p/base/transportcontroller.h b/webrtc/p2p/base/transportcontroller.h
index a46ce00dbc329a8f4627cca1318d06139572a476..a6fa70e01b46ef145b002929bda87dfb59aeae9e 100644
--- a/webrtc/p2p/base/transportcontroller.h
+++ b/webrtc/p2p/base/transportcontroller.h
@@ -113,7 +113,7 @@ class TransportController : public sigslot::has_slots<>,
 
   // Creates a channel if it doesn't exist. Otherwise, increments a reference
   // count and returns an existing channel.
-  virtual TransportChannel* CreateTransportChannel_n(
+  virtual DtlsTransportInternal* CreateTransportChannel_n(
       const std::string& transport_name,
       int component);
 
@@ -131,8 +131,8 @@ class TransportController : public sigslot::has_slots<>,
     return certificate_;
   }
   std::vector<std::string> transport_names_for_testing();
-  std::vector<TransportChannelImpl*> channels_for_testing();
-  TransportChannelImpl* get_channel_for_testing(
+  std::vector<DtlsTransportInternal*> channels_for_testing();
+  DtlsTransportInternal* get_channel_for_testing(
       const std::string& transport_name,
       int component);
 
@@ -167,7 +167,7 @@ class TransportController : public sigslot::has_slots<>,
   virtual TransportChannelImpl* CreateIceTransportChannel_n(
       const std::string& transport_name,
       int component);
-  virtual TransportChannelImpl* CreateDtlsTransportChannel_n(
+  virtual DtlsTransportInternal* CreateDtlsTransportChannel_n(
       const std::string& transport_name,
       int component,
       TransportChannelImpl* ice);