Wire-up BWE feedback for audio receive streams.

webrtc/voice_engine/channel.cc

 /*
  *  Copyright (c) 2012 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 2909 matching lines @@
 void Channel::EnableSendTransportSequenceNumber(int id) {
   int ret =
       SetSendRtpHeaderExtension(true, kRtpExtensionTransportSequenceNumber, id);
   RTC_DCHECK_EQ(0, ret);
 }
 
 void Channel::SetCongestionControlObjects(
     RtpPacketSender* rtp_packet_sender,
     TransportFeedbackObserver* transport_feedback_observer,
     PacketRouter* packet_router) {
-  RTC_DCHECK(feedback_observer_proxy_.get());
-  RTC_DCHECK(seq_num_allocator_proxy_.get());
-  RTC_DCHECK(rtp_packet_sender_proxy_.get());
   RTC_DCHECK(packet_router != nullptr || packet_router_ != nullptr);

[the sun, 2015/12/22 00:14:14]

Since we are relying on the channel only being used for either of send and
receive, and there being nothing to prevent the same channel id from being
specified in the Config for AudioReceive/SendStreams, it would be good to have
DCHECKs here to cover the expected cases:

1. internal objects null && all arguments non-null
2. internal objects null && packet router non-null
3. internal objects all non-null && all arguments null
4. packet_router_ non null && all arguments null

...if it is possible to write that in a way which isn't atrocious...

[stefan-webrtc, 2016/01/07 13:43:41]

I think it's non-trivial to test those without knowing if the channel is used
for sending or receiving. That is currently unknown and I'd prefer not wiring up
something like that for this cl.

What I can check is that if all members are null, then at least the
packet_router parameter should not be null. Since we allow calling with null on
all parameters even if SetCongestionControlObjects() weren't called in the
constructor of AudioReceiveStream, we can't check that some of the members are
non-null when all parameters are null. Not sure if it's worth adding getters to
all proxies just to be able to do this one DCHECK though?

-  feedback_observer_proxy_->SetTransportFeedbackObserver(
-      transport_feedback_observer);
-  seq_num_allocator_proxy_->SetSequenceNumberAllocator(packet_router);
-  rtp_packet_sender_proxy_->SetPacketSender(rtp_packet_sender);
+  if (transport_feedback_observer) {
+    RTC_DCHECK(feedback_observer_proxy_.get());
+    feedback_observer_proxy_->SetTransportFeedbackObserver(
+        transport_feedback_observer);
+  }
+  if (rtp_packet_sender) {
+    RTC_DCHECK(rtp_packet_sender_proxy_.get());
+    rtp_packet_sender_proxy_->SetPacketSender(rtp_packet_sender);
+  }
+  if (seq_num_allocator_proxy_.get())
+    seq_num_allocator_proxy_->SetSequenceNumberAllocator(packet_router);
   _rtpRtcpModule->SetStorePacketsStatus(rtp_packet_sender != nullptr, 600);
   if (packet_router != nullptr) {
     packet_router->AddRtpModule(_rtpRtcpModule.get());
   } else {
     packet_router_->RemoveRtpModule(_rtpRtcpModule.get());
   }
   packet_router_ = packet_router;
 }
 
 void Channel::SetRTCPStatus(bool enable) {
@@ skipping 1155 matching lines @@
   int64_t min_rtt = 0;
   if (_rtpRtcpModule->RTT(remoteSSRC, &rtt, &avg_rtt, &min_rtt, &max_rtt)
       != 0) {
     return 0;
   }
   return rtt;
 }
 
 }  // namespace voe
 }  // namespace webrtc