I think the "Chrome failed to start our game" help button needs to be updated.
When you go to about:flags the "GPU compositing" option is no longer available.
On the left, I have the help button link open, and on the right is my about:flags.

Now, what I did to get to get PL running, is simply used the "Reset all to default" button.



So yeah. But like I said I think^ it needs to be updated. It just might be my pc.