Chrome Version:68.0.3433.0/10689.0.0 dev-channel Daisy,Reks,Candy
OS: Chrome OS

What steps will reproduce the problem?
(1)Sign into user >> Launch chrome 
(2)In ubertray >> click on 'Lock' symbol and observe the shelf area in lock screen

Actual: Shelf shadow glimpse is seen while we lock screen
Expected:no such shadow glimpse should be seen at shelf of lock screen

This is a Regression issue seen as same is working fine in 63.0.3239.149/10032.88.0

Note:
1.Issue is not seen in Linux,Windows OS
2.Issue is seen from M-64,M-65 stable,M-67 beta

Attached the screencast for reference..
 

Deleted: Actual.mp4 5.0 MB

	Actual.mp4 5.0 MB View Download

Deleted: Expected.mp4 4.9 MB

	Expected.mp4 4.9 MB View Download