Results for 100 runs below. The text diff is likely due to needing to tweak the tolerance values. The timeouts, however, are unclear and my initial logging investigation to better understand was inconclusive. Filing this bug to track as follow-up work.

[18/100] compositing/layer-creation/toggle-animated-iframe-visibility.html failed unexpectedly (test timed out)
[25/100] compositing/layer-creation/toggle-animated-iframe-visibility.html failed unexpectedly (test timed out)
[31/100] compositing/layer-creation/toggle-animated-iframe-visibility.html failed unexpectedly (test timed out)
[66/100] compositing/layer-creation/toggle-animated-iframe-visibility.html failed unexpectedly (text diff)
[71/100] compositing/layer-creation/toggle-animated-iframe-visibility.html failed unexpectedly (text diff)
[77/100] compositing/layer-creation/toggle-animated-iframe-visibility.html failed unexpectedly (test timed out)

Unassigning self from bugs that I don't expect to be able to get to soon in case someone else is able to pick them up.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot