I have a WIP patch[1] that changes layout tests running in single-threaded mode to actually run through the update phases in the compositor during the main frame, which is closer to production behaviour. This is making media/video-poster-after-loadedmetadata.html fail consistently.

I ran the test with threaded compositing to verify if this was a bug with the patch itself or the test and I get the same failure when running with threaded compositing. The interesting part is that while threaded compositing makes it flaky, it fails quite consistently with the patch above. Seems like a timing issue which was racy in threaded mode but we hit consistently now.

mlamouri@, would you be the correct person to own this? I'm marking the test flaky for now.

[1]: https://chromium-review.googlesource.com/c/chromium/src/+/900205