Chrome Version: 66.0.3359.158 (Official Build) (64-bit)
Chrome OS Version: 10452.85.0 (Official Build) stable-channel eve
Chrome OS Platform: Pixelbook

Steps To Reproduce:
(1) Log in.
(2) Move mouse cursor to the bottom-left corner of the screen, where the Shut down and Sign out buttons are on the lock screen.
(3) Press Search + L to lock the screen.
(4) Wait until the screen/device goes to sleep.
(5) Click the trackpad to wake up the screen/device.

Expected Result: The screen/device wakes up and displays the lock screen, and the click does not act on the button you were (potentially unknowingly) hovering over.

Actual Result: The click acts on the button you were hovering over and either logs you out or shuts down the device, depending on which button you were hovering over.

How frequently does this problem reproduce? (Always, sometimes, hard to
reproduce?)
It always reproduces when this specific sequence of events is followed. In regular usage, it would happen every once in a while because the cursor isn't always over those buttons when the screen is locked.

What is the impact to the user, and is there a workaround? If so, what is
it?
The user can lose work on things that are currently in progress. Users can work around this by not leaving the mouse cursor in the problematic area when locking the screen, but if the user isn't aware of the problem, it can be very easy to leave the cursor there, as that is also where the app icons in the taskbar are.