Chrome Version:68.0.3416.0/10638.0.0 dev channel Daisy,Candy,Reks
OS: Chrome OS

What steps will reproduce the problem?
(1)Sign into user and Sign out 
(2)In Sign out screen >> Click on Add person and observe 

Actual: Add person button is seen and clickable also, even after opening Add person overlay
Expected: Add person button shouldn't be seen when Add person overlay is opened already

This is a Regression issue as same is working fine in 68.0.3400.0/10598.0.0 dev 

Note:Issue is not seen in Linux,Windows OS

Attached the screenshot for reference..

@jdufault : Could you please confirm the issue.
 

Deleted: Actual.mp4 4.3 MB

	Actual.mp4 4.3 MB View Download

Deleted: Expected.mp4 6.2 MB

	Expected.mp4 6.2 MB View Download