Fix for scenario where m-line is revived after being set to port 0.

talk/app/webrtc/peerconnection.cc

Index: talk/app/webrtc/peerconnection.cc
diff --git a/talk/app/webrtc/peerconnection.cc b/talk/app/webrtc/peerconnection.cc
index 0d519b280b9f77485e4e648cf1697274bbd448fa..801b69b6147540b6c41cc86b68dfb35301902958 100644
--- a/talk/app/webrtc/peerconnection.cc
+++ b/talk/app/webrtc/peerconnection.cc
@@ -949,6 +949,15 @@ void PeerConnection::SetLocalDescription(
   const cricket::ContentInfo* audio_content =
       GetFirstAudioContent(desc->description());
   if (audio_content) {
+    if (audio_content->rejected) {
+      audio_rejected_ = true;
+    } else if (audio_rejected_) {

[pthatcher1, 2015/11/11 00:45:02]

Can we get the equivalent of audio_rejected_ by looking at local_description_
before line 934?  Then we wouldn't need the extra member variable.

[Taylor Brandstetter, 2015/11/11 01:33:29]

It gets more complex if we go that route. We have to check both the remote and
local description. But really what we're interested in is the last answer
description (assuming port 0 offers must be met with port 0 answers). I started
implementing this but it started to feel like overkill for a termporary hack.

+      // If going from rejected to unrejected, need to reconfigure senders and
+      // receivers.
+      audio_rejected_ = false;
+      ReconfigureSenders(cricket::MEDIA_TYPE_AUDIO);
+      ReconfigureReceivers(cricket::MEDIA_TYPE_AUDIO);

[pthatcher1, 2015/11/11 00:45:02]

Should we have a ReconfigureSenderAndReceivers method?

[Taylor Brandstetter, 2015/11/11 01:33:29]

Done.

+    }
     const cricket::AudioContentDescription* audio_desc =
         static_cast<const cricket::AudioContentDescription*>(
             audio_content->description);
@@ -958,6 +967,15 @@ void PeerConnection::SetLocalDescription(
   const cricket::ContentInfo* video_content =
       GetFirstVideoContent(desc->description());
   if (video_content) {
+    if (video_content->rejected) {
+      video_rejected_ = true;
+    } else if (video_rejected_) {
+      // If going from rejected to unrejected, need to reconfigure senders and
+      // receivers.
+      video_rejected_ = false;
+      ReconfigureSenders(cricket::MEDIA_TYPE_VIDEO);
+      ReconfigureReceivers(cricket::MEDIA_TYPE_VIDEO);
+    }
     const cricket::VideoContentDescription* video_desc =
         static_cast<const cricket::VideoContentDescription*>(
             video_content->description);
@@ -1023,6 +1041,15 @@ void PeerConnection::SetRemoteDescription(
   // and MediaStreams.
   const cricket::ContentInfo* audio_content = GetFirstAudioContent(remote_desc);
   if (audio_content) {
+    if (audio_content->rejected) {
+      audio_rejected_ = true;
+    } else if (audio_rejected_) {
+      // If going from rejected to unrejected, need to reconfigure senders and
+      // receivers.
+      audio_rejected_ = false;
+      ReconfigureSenders(cricket::MEDIA_TYPE_AUDIO);
+      ReconfigureReceivers(cricket::MEDIA_TYPE_AUDIO);
+    }
     const cricket::AudioContentDescription* desc =
         static_cast<const cricket::AudioContentDescription*>(
             audio_content->description);
@@ -1036,6 +1063,15 @@ void PeerConnection::SetRemoteDescription(
   // and MediaStreams.
   const cricket::ContentInfo* video_content = GetFirstVideoContent(remote_desc);
   if (video_content) {
+    if (video_content->rejected) {
+      video_rejected_ = true;
+    } else if (video_rejected_) {
+      // If going from rejected to unrejected, need to reconfigure senders and
+      // receivers.
+      video_rejected_ = false;
+      ReconfigureSenders(cricket::MEDIA_TYPE_VIDEO);
+      ReconfigureReceivers(cricket::MEDIA_TYPE_VIDEO);
+    }
     const cricket::VideoContentDescription* desc =
         static_cast<const cricket::VideoContentDescription*>(
             video_content->description);
@@ -1934,6 +1970,22 @@ PeerConnection::FindReceiverForTrack(MediaStreamTrackInterface* track) {
       });
 }
 
+void PeerConnection::ReconfigureSenders(cricket::MediaType media_type) {
+  for (const auto& sender : senders_) {
+    if (sender->media_type() == media_type) {
+      sender->Reconfigure();
+    }
+  }
+}
+
+void PeerConnection::ReconfigureReceivers(cricket::MediaType media_type) {
+  for (const auto& receiver : receivers_) {
+    if (receiver->media_type() == media_type) {
+      receiver->Reconfigure();
+    }
+  }
+}
+
 PeerConnection::TrackInfos* PeerConnection::GetRemoteTracks(
     cricket::MediaType media_type) {
   RTC_DCHECK(media_type == cricket::MEDIA_TYPE_AUDIO ||