2073296 - RTC(Dtls|Ice)Transports aren't updated correctly when a transceiver is removed

Status: NEW

(Core :: WebRTC: Signaling, defect, P3)

Description

[Byron Campen [:bwc]]

When a transceiver is negotiated away via a disabled m-section, the transport objects are supposed to transition to "closed" in a queued task (queued from the success steps for setting a description, presumably). However, JsepSessionImpl clears the transport id on the JsepTransport when this happens:

https://searchfox.org/firefox-main/source/dom/media/webrtc/jsep/JsepTransport.h#80
https://searchfox.org/firefox-main/source/dom/media/webrtc/jsep/JsepSessionImpl.cpp#1233
https://searchfox.org/firefox-main/source/dom/media/webrtc/jsep/JsepSessionImpl.cpp#927

This leads to the RTCDtlsTransport being unset here:

https://searchfox.org/firefox-main/source/dom/media/webrtc/jsapi/PeerConnectionImpl.cpp#4337-4338,4340,4352

Which in turn prevents that object from being updated at all here:

https://searchfox.org/firefox-main/source/dom/media/webrtc/jsapi/PeerConnectionImpl.cpp#3180

We need some wpt that check the transport is still set, as well as timing verification of the transition to "closed".