It looks like this CL is causing multiple follow-on test issues
https://chromium-review.googlesource.com/c/chromium/src/+/1318893

These include:
Issue 906700,
issue 906834,
and maybe some others.

It's a pretty big CL so this sheriff has been working on fixing individual issues rather than rolling back the whole thing, but that may turn out to be a lost cause.