Remove BaseChannel's dependency on TransportController.

webrtc/api/webrtcsession_unittest.cc

Index: webrtc/api/webrtcsession_unittest.cc
diff --git a/webrtc/api/webrtcsession_unittest.cc b/webrtc/api/webrtcsession_unittest.cc
index f739c16abec962795df2e1fe06fe330c5c021473..3e1a5833e5e3020c9e1302c2b3fc974c41edc005 100644
--- a/webrtc/api/webrtcsession_unittest.cc
+++ b/webrtc/api/webrtcsession_unittest.cc
@@ -306,7 +306,7 @@ class WebRtcSessionForTest : public webrtc::WebRtcSession {
     if (!ch) {
       return nullptr;
     }
-    return ch->transport_channel();
+    return ch->rtp_transport();
   }
 
   rtc::PacketTransportInterface* rtcp_transport_channel(
@@ -314,7 +314,7 @@ class WebRtcSessionForTest : public webrtc::WebRtcSession {
     if (!ch) {
       return nullptr;
     }
-    return ch->rtcp_transport_channel();
+    return ch->rtcp_transport();
   }
 };