Version: 53.0.2785.36 dev (has been true for quite a while)
OS: 8530.35.0 (Official Build) dev-channel veyron_minnie

What steps will reproduce the problem?
(1) Sign out so you're at the login screen, OR
    lock the screen so you're at the lock screen
(2) Scroll down with two fingers on the touchpad, OR
    scroll down on the touchscreen
(3) Watch the picture of your user account scroll up

What is the expected output?

Those screens should be static and unscrollable, at least when there's only one user account.