Remove BaseChannel's dependency on TransportController.

webrtc/p2p/base/faketransportcontroller.h

Index: webrtc/p2p/base/faketransportcontroller.h
diff --git a/webrtc/p2p/base/faketransportcontroller.h b/webrtc/p2p/base/faketransportcontroller.h
index d42a93ddae9f95cf1558f9d32f3273f5e9a113c3..cfc59ed131e3af37b43e621581cea19806ef9ad4 100644
--- a/webrtc/p2p/base/faketransportcontroller.h
+++ b/webrtc/p2p/base/faketransportcontroller.h
@@ -443,6 +443,11 @@ class FakeTransportController : public TransportController {
     return new FakeCandidatePair(local_candidate, remote_candidate);
   }
 
+  void OnDestroyRtcpTransport(const std::string& transport_name) {

[Taylor Brandstetter, 2017/01/12 22:39:02]

Can this slot either be moved to the test where it's used, or remove the "On"
from the name? Usually, methods named like "OnFoo" are private.

[Zhi Huang, 2017/01/13 00:12:47]

I'll go with the simpler one.

+    DestroyTransportChannel_n(transport_name,
+                              cricket::ICE_CANDIDATE_COMPONENT_RTCP);
+  }
+
  protected:
   // The ICE channel is never actually used by TransportController directly,
   // since (currently) the DTLS channel pretends to be both ICE + DTLS. This