Going to speculatively try reverting https://chromium-review.googlesource.com/q/I91b9340251c2cd0b60e3b3f66d450a4791113007, although I'm not convinced it's the actual cause of the flakiness.

There have been no flakes in 6 builds after I reverted the change, but there weren't any in the 5 builds before I landed the revert... so it's maybe too soon to say if the flakes have actually gone. Leaving this on the sheriff queue for now.

Hmm, test is still quite flaky according to the flakiness dashboard, but the tests usually passes after a retry.

For example: https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8935546745889735808/+/steps/interactive_ui_tests_on_Ubuntu-16.04/0/stdout

The error is:

[ RUN      ] BookmarkBarViewTest24.ContextMenusKeyboardEscape
X Error of failed request:  BadWindow (invalid Window parameter)
  Major opcode of failed request:  3 (X_GetWindowAttributes)
  Resource id in failed request:  0x60000d
  Serial number of failed request:  473
  Current serial number in output stream:  474

I'm guessing it's something to do with X server?

Oh nvm, I was reading the flakiness dashboard wrong. The flakinesss dashboard has been green for quite a while :)

I'm unable to reproduce or narrow this down. What is the current status of this test? How do I find out?

Closing out. Already landed in Canary. Still cannot reproduce any flakiness.