Chrome Version:  65.0.3299.0/10259.0.0  dev-channel Minnie,Blaze and Quawks 
OS: Chrome

Sample URL : http://www.sample-videos.com/

What steps will reproduce the problem?
(1)Sign in to user ->Now go to above URL -> download any file(Ex: Download any 10Mb video)
(2)Now go to Files App  -> Select downloaded video -> Right Click and select 'Open with Video Player' option 
(3)Now hover mouse on 'Pause' ,'Full Screen' Icons and observe for Tool tip
(Please refer Video )

Note : Pause the Video and Click on 'Full screen' option -> Now hover mouse on 'Play' , 'Exit Full Screen' icons and observe for Tool tip

Expected: Tool tip should be seen on hovering mouse on 'Pause' ,'Full Screen' , 'Play' , 'Exit Full Screen' Icons
Actual: Instead Tool tip is seen Missing

This is Non-Regression Issue seen form M-55

@fukino : Please confirm the Issue
 

Deleted: Actual_NoTooltip.webm 2.7 MB

	Actual_NoTooltip.webm 2.7 MB View Download