Seen while running try-jobs from:
https://chromium-review.googlesource.com/c/524513/

Sample bot link:
https://build.chromium.org/p/tryserver.chromium.linux/builders/linux_chromium_chromeos_ozone_rel_ng/builds/424664

So my best guess here is that there is a focus race on the WebView ... its content loads and then the keypress is sent, but if the WebView hasn't got focus yet then the keypress goes to the embedder, and the test times out?

I'll try adding a focus wait to the test.

This is fixed.