Remove BaseChannel's dependency on TransportController.

webrtc/p2p/base/transportcontroller.cc

Index: webrtc/p2p/base/transportcontroller.cc
diff --git a/webrtc/p2p/base/transportcontroller.cc b/webrtc/p2p/base/transportcontroller.cc
index 4a3a00e10f0e2831e4eefcf6bd53d229086b0d84..80fe60c0cd48a1b9bd2f5398a30c79d068dd8464 100644
--- a/webrtc/p2p/base/transportcontroller.cc
+++ b/webrtc/p2p/base/transportcontroller.cc
@@ -227,6 +227,14 @@ void TransportController::SetMetricsObserver(
                                metrics_observer));
 }
 
+TransportChannel* TransportController::CreateTransportChannel(
+    const std::string& transport_name,
+    int component) {
+  return network_thread_->Invoke<TransportChannel*>(
+      RTC_FROM_HERE, rtc::Bind(&TransportController::CreateTransportChannel_n,
+                               this, transport_name, component));
+}
+
 TransportChannel* TransportController::CreateTransportChannel_n(
     const std::string& transport_name,
     int component) {
@@ -288,6 +296,14 @@ TransportChannel* TransportController::CreateTransportChannel_n(
   return dtls;
 }
 
+void TransportController::DestroyTransportChannel(
+    const std::string& transport_name,
+    int component) {
+  network_thread_->Invoke<void>(
+      RTC_FROM_HERE, rtc::Bind(&TransportController::DestroyTransportChannel_n,
+                               this, transport_name, component));
+}
+
 void TransportController::DestroyTransportChannel_n(
     const std::string& transport_name,
     int component) {