Version: 51.0.2694.1
OS: ChromeOS

What steps will reproduce the problem?
(1) Use ChromeOS for some time; my uptime is 3 days, and I have three Chrome windows, three app windows and multiple tabs in each Chrome window.
(2) Tap on different tabs & windows, to focus them.

What is the expected output?

Expect that they immediately re-render to be focused.

What do you see instead?

Instead the Chrome tab-strip, especially, tends to flicker transparent, briefly, before re-rendering normally.

I've also seen instances where Chrome Apps open up and then when some other window is opened while their content is still loading, then part of the first app window ends up rendered transparent, until that window is next re-composited, e.g. because it becomes focused, or is moved.

Currently observing this on M51 dev-channel, but it's been happening for weeks, so I think it regressed in M50.