Hey Lindsay, is there any chance you could allocate some test team time to find repro steps for this? I've seen this in the wild but I don't know how to repro. 
If it's impossible at the moment, please send this back to me, I'll try more. 

Sure, we'll take a look and update.

I ran into the same issue yesterday with an older version of canary. But after upgrading to latest canary M69.0.3473.0 I can no longer reproduce.

But as far as the steps, it reproduces if you install any older version of canary. 
Ex: Fresh Install canary.ipa from this location https://pantheon.corp.google.com/storage/browser/chrome-signed/ios-G1N/69.0.3465.0/iphoneos11.2/ios-canary/1051/
Launch Chrome,
Navigate to google.com
Tap on omnibox
Long tap selection.
Selection handlers are displayed in black color.

https://drive.google.com/file/d/1W3eKdYNaULKsJLcpubJRx7GnC07n29r8/view

Thank you! This is great news, it means I fixed it with one of the CLs that introduced the proper tint color. Thank you once again!