Chrome Version:
Google Chrome	61.0.3128.3 (Official Build) dev (64-bit)
Revision	630da925fd672bb784e9a100de64ae385dc0d94c-refs/branch-heads/3128@{#4}
OS	Linux

What steps will reproduce the problem?
(1) Navigate to a new-ish site that will ask to show you notifications.
(2) Have the bubble pop-up: "<site> wants to: Show notifications"
or some other bubble
(3) Try to press ^Q, ^W, ^T, ^R, ^tab, etc.

What is the expected result?
I would expect the control keys to work.

What happens instead?
The bubble is obviously focused, capturing keys and dropping them.

The bubble seems to handle tabbing away (with the mouse) and coming
back, so it doesn't seem necessary to force the user's attention.

It would appear that the bubble simply needs to forward keys that
it doesn't handle.