Chrome Version: 68.0.3416.0 (Official Build) canary (64-bit)
OS: Windows 7, Windows 8

What steps will reproduce the problem?
(1)hover cursor over the X in the taskbar which closes a tab

What is the expected result?
I see a white X in a red circle.

What happens instead?
I see a black X in a red circle (attached).  This is IMHO less attractive, and the contrast is much worse which may be an accessibility issue.