Filed by: mlaza [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=373178363&repo=mozilla-central
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/ZEVjwqJaQfC5uFDvoS5UJQ/runs/0/artifacts/public/logs/live_backing.log

[task 2022-04-02T12:28:09.902Z] 12:28:09     INFO - TEST-PASS | dom/media/webrtc/tests/mochitests/test_peerConnection_disabledVideoPreNegotiation.html | RTP flowing for video track {7fe87b6b-2c4a-47df-b266-6c5c12cab691} 
[task 2022-04-02T12:28:09.906Z] 12:28:09     INFO - Buffered messages finished
[task 2022-04-02T12:28:09.927Z] 12:28:09     INFO - TEST-UNEXPECTED-FAIL | dom/media/webrtc/tests/mochitests/test_peerConnection_disabledVideoPreNegotiation.html | Error in test execution: Error: Timeout for element _remote_{7fe87b6b-2c4a-47df-b266-6c5c12cab691} waitForMediaElementFlow@https://example.com/tests/dom/media/webrtc/tests/mochitests/pc.js:1757:23 ... waitForMediaFlow/<@https://example.com/tests/dom/media/webrtc/tests/mochitests/pc.js:1880:25 ... waitForMediaFlow@https://example.com/tests/dom/media/webrtc/tests/mochitests/pc.js:1880:10 ... PC_REMOTE_WAIT_FOR_MEDIA_FLOW@https://example.com/tests/dom/media/webrtc/tests/mochitests/templates.js:460:26 ... execute/</<@https://example.com/tests/dom/media/webrtc/tests/mochitests/head.js:1024:32 ...  
[task 2022-04-02T12:28:09.928Z] 12:28:09     INFO - SimpleTest.ok@https://example.com/tests/SimpleTest/SimpleTest.js:417:16
[task 2022-04-02T12:28:09.928Z] 12:28:09     INFO - execute/<@https://example.com/tests/dom/media/webrtc/tests/mochitests/head.js:1028:11
[task 2022-04-02T12:28:09.937Z] 12:28:09     INFO - TEST-FAIL | dom/media/webrtc/tests/mochitests/test_peerConnection_disabledVideoPreNegotiation.html | The author of the test has indicated that flaky timeouts are expected.  Reason: WebRTC inherently depends on timeouts 
[task 2022-04-02T12:28:09.943Z] 12:28:09     INFO - Closing peer connections
[task 2022-04-02T12:28:09.949Z] 12:28:09     INFO - Waiting for track {e18fdb69-4a80-4f16-8083-f27c2bed14f5} (video) to end.
[task 2022-04-02T12:28:09.958Z] 12:28:09     INFO - TEST-FAIL | dom/media/webrtc/tests/mochitests/test_peerConnection_disabledVideoPreNegotiation.html | The author of the test has indicated that flaky timeouts are expected.  Reason: WebRTC inherently depends on timeouts 
[task 2022-04-02T12:28:09.966Z] 12:28:09     INFO - GECKO(8804) | [Child 14032: Main Thread]: I/signaling [main|PeerConnectionImpl] PeerConnectionImpl.cpp:1908: Close: Closing PeerConnectionImpl {26c68e15-8d53-4486-a008-77424fe13bcc}; ending call
[task 2022-04-02T12:28:09.974Z] 12:28:09     INFO - GECKO(8804) | [Child 14032: Main Thread]: I/jsep [{26c68e15-8d53-4486-a008-77424fe13bcc} 1648902420787000 (id=8589934689 url=https://example.com/tests/dom/media/webrtc/tests/moc]: stable -> closed
[task 2022-04-02T12:28:09.980Z] 12:28:09     INFO - PeerConnectionWrapper (pcLocal): Closed connection.
[task 2022-04-02T12:28:09.987Z] 12:28:09     INFO - Waiting for track {7fe87b6b-2c4a-47df-b266-6c5c12cab691} (video) to end.
[task 2022-04-02T12:28:09.996Z] 12:28:09     INFO - TEST-FAIL | dom/media/webrtc/tests/mochitests/test_peerConnection_disabledVideoPreNegotiation.html | The author of the test has indicated that flaky timeouts are expected.  Reason: WebRTC inherently depends on timeouts 
[task 2022-04-02T12:28:10.003Z] 12:28:10     INFO - GECKO(8804) | [Child 14032: Main Thread]: I/signaling [main|PeerConnectionImpl] PeerConnectionImpl.cpp:1908: Close: Closing PeerConnectionImpl {3812ed4e-aa5b-4738-86a6-6f928f17b177}; ending call
[task 2022-04-02T12:28:10.011Z] 12:28:10     INFO - GECKO(8804) | [Child 14032: Main Thread]: I/jsep [{3812ed4e-aa5b-4738-86a6-6f928f17b177} 1648902420843000 (id=8589934689 url=https://example.com/tests/dom/media/webrtc/tests/moc]: stable -> closed
[task 2022-04-02T12:28:10.017Z] 12:28:10     INFO - PeerConnectionWrapper (pcRemote): Closed connection.
[task 2022-04-02T12:28:10.026Z] 12:28:10     INFO - TEST-FAIL | dom/media/webrtc/tests/mochitests/test_peerConnection_disabledVideoPreNegotiation.html | The author of the test has indicated that flaky timeouts are expected.  Reason: WebRTC inherently depends on timeouts 
[task 2022-04-02T12:28:10.033Z] 12:28:10     INFO - TEST-PASS | dom/media/webrtc/tests/mochitests/test_peerConnection_disabledVideoPreNegotiation.html | Event target should be the correct track 

Hi Zaggy1024, could this be a regression of bug 1760804?

It seems doubtful, here is a try with the media mochitests that succeeded for that patch. I'm not sure if it's possible that the difference in the tasks run caused the error to be hidden in my try (windows10-aarch64 vs windows10-64-2004, not sure if those are intended to be different), but that seems unlikely.

I would have to guess that this failure is related to Bug 1741244, since it has a lot of landed patches related to WebRTC on Windows.

For my own peace of mind, I wanted to confirm that it wasn't my revision introduced this regression. It appears that it is still present in a more recent merge than the one where my patch was backed out. The mda mochitest result for that changelist is here: https://treeherder.mozilla.org/jobs?repo=mozilla-central&revision=2d8724cbbdddcea2537f92a18cec4eae6bec0fe7&selectedTaskRun=F7G_ZfBdRtmdmmbyb5b5Dg.0

There's another failure that might be related to this one as retriggers only point to this bug. Here's the failure log .
There are these failure lines too in the log: TEST-FAIL | dom/media/webrtc/tests/mochitests/test_peerConnection_addAudioTrackToExistingVideoStream.html | The author of the test has indicated that flaky timeouts are expected. Reason: WebRTC inherently depends on timeouts

Looks like the failures started with the changes in Bug 1741244 here.

Set release status flags based on info from the regressing bug 1741244

This went away around April 27. Looking at the pushlog for when this went green (https://hg.mozilla.org/mozilla-central/pushloghtml?changeset=23768574eb6d1c1191228316adbc082aaf3a7fd5), bug 1766311 looks highly likely.