Remove BaseChannel's dependency on TransportController.

webrtc/api/webrtcsession.cc

Index: webrtc/api/webrtcsession.cc
diff --git a/webrtc/api/webrtcsession.cc b/webrtc/api/webrtcsession.cc
index 5d414baac2f89c60df48bfd9d451132eeb7d7b8b..ed408ade88f95d68fb7f1bafe86a49b2811a20e7 100644
--- a/webrtc/api/webrtcsession.cc
+++ b/webrtc/api/webrtcsession.cc
@@ -1039,7 +1039,6 @@ bool WebRtcSession::EnableBundle(const cricket::ContentGroup& bundle) {
     return false;
   }
   const std::string& transport_name = *first_content_name;
-  cricket::BaseChannel* first_channel = GetChannel(transport_name);
 
 #ifdef HAVE_QUIC
   if (quic_data_transport_ &&
@@ -1050,8 +1049,8 @@ bool WebRtcSession::EnableBundle(const cricket::ContentGroup& bundle) {
   }
 #endif
 
-  auto maybe_set_transport = [this, bundle, transport_name,
-                              first_channel](cricket::BaseChannel* ch) {
+  auto maybe_set_transport = [this, bundle,
+                              transport_name](cricket::BaseChannel* ch) {
     if (!ch || !bundle.HasContentName(ch->content_name())) {
       return true;
     }
@@ -1062,7 +1061,15 @@ bool WebRtcSession::EnableBundle(const cricket::ContentGroup& bundle) {
       return true;
     }
 
-    if (!ch->SetTransport(transport_name)) {
+    cricket::TransportChannel* rtp_transport =
+        transport_controller_->CreateTransportChannel(
+            transport_name, cricket::ICE_CANDIDATE_COMPONENT_RTP);
+    cricket::TransportChannel* rtcp_transport = nullptr;
+    if (ch->ShouldCreateRtcpTransport()) {
+      rtcp_transport = transport_controller_->CreateTransportChannel(
+          transport_name, cricket::ICE_CANDIDATE_COMPONENT_RTCP);
+    }
+    if (!ch->SetTransport(rtp_transport, rtcp_transport)) {

[Taylor Brandstetter, 2017/01/09 22:50:42]

I think there's an opportunity here to reduce some thread hops. Currently each
"SetTransport" will hop to the network thread, but instead, we could invoke
"EnableBundle" on the network thread.

       LOG(LS_WARNING) << "Failed to enable BUNDLE for " << ch->content_name();
       return false;
     }
@@ -1670,6 +1677,8 @@ bool WebRtcSession::CreateVoiceChannel(const cricket::ContentInfo* content,
   SignalVoiceChannelCreated();
   voice_channel_->SignalSentPacket.connect(this,
                                            &WebRtcSession::OnSentPacket_w);
+  voice_channel_->SignalDestroyTransport.connect(
+      this, &WebRtcSession::OnDestroyTransport);

[Taylor Brandstetter, 2017/01/09 22:50:42]

It would be nice if the creation *and* destruction were both handled in
WebRtcSession. Would that be feasible? The cases where DestroyTransportChannel
should be called are:

* When the BaseChannel is destroyed
* When SetTransport is called
* When ActivateRtcpMux is called

This sounds reasonable to handle here, and that would avoid needing to have
"SignalDestroyTransport".

[Zhi Huang, 2017/01/12 03:47:46]

Done.

   return true;
 }
 
@@ -1694,6 +1703,8 @@ bool WebRtcSession::CreateVideoChannel(const cricket::ContentInfo* content,
   SignalVideoChannelCreated();
   video_channel_->SignalSentPacket.connect(this,
                                            &WebRtcSession::OnSentPacket_w);
+  video_channel_->SignalDestroyTransport.connect(
+      this, &WebRtcSession::OnDestroyTransport);
   return true;
 }
 
@@ -1733,6 +1744,8 @@ bool WebRtcSession::CreateDataChannel(const cricket::ContentInfo* content,
 
   SignalDataChannelCreated();
   data_channel_->SignalSentPacket.connect(this, &WebRtcSession::OnSentPacket_w);
+  data_channel_->SignalDestroyTransport.connect(
+      this, &WebRtcSession::OnDestroyTransport);
   return true;
 }
 
@@ -2107,4 +2120,9 @@ void WebRtcSession::OnDtlsHandshakeError(rtc::SSLHandshakeError error) {
         static_cast<int>(rtc::SSLHandshakeError::MAX_VALUE));
   }
 }
+
+void WebRtcSession::OnDestroyTransport(const std::string& transport_name,
+                                       int component) {
+  transport_controller_->DestroyTransportChannel(transport_name, component);
+}
 }  // namespace webrtc