Chrome Version: 61.0.3147.0/9717.0.0 dev channel Panther,Jerry and Falco
OS: Chrome

What steps will reproduce the problem?
(1)Sign into User  -> Now download Images or save pages (Ex: upto 5-6)
(2)Don't close any Notifications -> Number should be seen at Notification Icon -> Now click on Notification number(Ex: 6)
(3)Now close any Notification available at top or Middle -> Observe unnecessary space is seen at bottom of overlay
(4)Hover mouse outside of the Notification overlay and observe unnecessary space is still seen  (Please refer Video)

Note: Click notification icon to close overlay and again click on notification Icon -> observe now unnecessary space is not seen

Expected: Unnecessary space should be not seen on hovering mouse outside of Overlay 
Actual: Instead unnecessary space is still seen

This is Regression Issue as same is working fine in 57.0.2987.154/	9202.71.0 Stable-channel Candy device

@Yoshiki: Please confirm the Issue
 

Deleted: Actual_Notifications.webm 1.3 MB

	Actual_Notifications.webm 1.3 MB View Download

Deleted: Expected_Notifications.webm 1.6 MB

	Expected_Notifications.webm 1.6 MB View Download