Modified PeerConnection and WebRtcSession for end-to-end QuicDataChannel usage.

webrtc/api/quicdatachannel.cc

 /*
  *  Copyright 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 210 matching lines @@
 }
 
 bool QuicDataChannel::SetTransportChannel(
     cricket::QuicTransportChannel* channel) {
   RTC_DCHECK(signaling_thread_->IsCurrent());
 
   if (!channel) {
     LOG(LS_ERROR) << "|channel| is NULL. Cannot set transport channel.";
     return false;
   }
-  if (quic_transport_channel_) {
-    if (channel == quic_transport_channel_) {
-      LOG(LS_WARNING) << "Ignoring duplicate transport channel.";
-      return true;
-    }
-    LOG(LS_ERROR) << "|channel| does not match existing transport channel.";
-    return false;
+
+  if (channel == quic_transport_channel_) {
+    LOG(LS_WARNING) << "Ignoring duplicate transport channel.";
+    return true;
   }
 
+  // Disconnect from the old transport channel.
+  if (quic_transport_channel_) {
+    quic_transport_channel_->SignalReadyToSend.disconnect(this);
+    quic_transport_channel_->SignalClosed.disconnect(this);
+  }
+  // Set new transport channel.

[Taylor Brandstetter, 2016/07/21 23:39:57]

Is it possible to switch transports in the middle of a session? Couldn't that
cause packets to be lost, since we're losing the state of the streams in the old
transport?

[pthatcher1, 2016/07/22 17:57:57]

We should at least do this:
 
if (state_ == kOpen) {
  return false;
}


Otherwise, I think changing the transport channel will work.

[Taylor Brandstetter, 2016/07/22 19:04:56]

If we base the success of "Set___Description" on the open state of the data
channel, that seems like it's asking for trouble. Sometimes it will succeed and
sometimes it won't depending on timing. I'd prefer to just always disallow it,
and tell people to use max-bundle or force bundling on the data transport.

[Zhi Huang, 2016/07/25 23:40:36]

I will revert this change for now. I think we might need this when negotiation.
But that comes later.

   quic_transport_channel_ = channel;
   LOG(LS_INFO) << "Setting QuicTransportChannel for QUIC data channel " << id_;
   DataState data_channel_state = worker_thread_->Invoke<DataState>(
       RTC_FROM_HERE, rtc::Bind(&QuicDataChannel::SetTransportChannel_w, this));
   SetState_s(data_channel_state);
   return true;
 }
 
 DataChannelInterface::DataState QuicDataChannel::SetTransportChannel_w() {
   RTC_DCHECK(worker_thread_->IsCurrent());
@@ skipping 137 matching lines @@
 
 size_t QuicDataChannel::GetNumWriteBlockedStreams() const {
   return write_blocked_quic_streams_.size();
 }
 
 size_t QuicDataChannel::GetNumIncomingStreams() const {
   return incoming_quic_messages_.size();
 }
 
 }  // namespace webrtc