This is an Touch specific Regression issue broken in M-63, will soon update bisect info.
Good Build: 63.0.3209.0 
Bad Build: 63.0.3210.0 

You are probably looking for a change made after 500506 (known good), but no later than 500507 (first known bad).

CHANGELOG URL:

The script might not always return single CL as suspect as some perf builds might get missing due to failure.

https://chromium.googlesource.com/chromium/src/+log/03ae8b26cac782874390cadc5fd5faa6025cf5ba..e976a3897d7a8abbbacce4c2622cc5ecf5a7b067

Suspect:https://chromium.googlesource.com/chromium/src/+/e976a3897d7a8abbbacce4c2622cc5ecf5a7b067

@girard: Could you please look into the issue, pardon me if it has nothing to do with your changes and if possible please assign it to concern owner.

Adding RB Label as this is a recent Regression. Please remove if not required.
Thank You.

When I test this on my device, the "shadow" does show up, but only remains for as long as the second touch (the touch on the page) is in contact. Once I lift my finger from the page, the shadow goes away.

Is this what you're seeing as well?

With respect to Comment 3:

Issue is always seen after performing step-2 (i.e Tap/touch on Guest avatar icon (Avatar bubble gets open) and tap/touch any where on the page.)

Faint focus on guest icon disappears when performing action like tap on tab strip area, omnibox, Learn more link and wrench menu.

Thank you. 

girard@,
Could you please look into this issue as per C#4 as it is marked as stable blocker.

Thanks..!!

girard@,
Friendly ping to get an update on this issue as per C#4.
Thanks..!!

Gentle ping to get an update on this issue as per C#4.

[Bulk Edit]
URGENT - PTAL.
M63 Stable promotion is coming soon and your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and get it merged into the release branch ASAP. Thank you.

M63 Stable promotion is coming soon and your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and request a merge to M63 ASAP. Thank you.

Based on comment #10, if this is blocked on 763223. The code was also reverted in https://chromium-review.googlesource.com/c/chromium/src/+/655645 which was merged to M61 and M62 as well. 

Is this bug indeed M63 regression in this case?

Agree this is not a regression because it's been public for two milestones.

Remains a P1 for M-64.

This doesn't seem like a P1 bug to me either. Demoting to P2 (feel free to correct me if I'm wrong).

--Chrome Identity automated triaging--

This bug is Assigned and has gone one month without any activity, so it is being moved to Available to indicate that it is not actively being worked on. If you are working on this bug, please mark yourself as the owner and move back to Assigned. Please see https://goo.gl/78kbny for more details. Please remove the Services>SignIn or UI>Browser>Profiles components if this bug isn't related to Chrome Identity.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

--Chrome Identity automated triaging--

This bug is Assigned and has gone one month without any activity, so it is being moved to Available to indicate that it is not actively being worked on. If you are working on this bug, please mark yourself as the owner and move back to Assigned. Please see https://goo.gl/78kbny for more details. Please remove the Services>SignIn or UI>Browser>Profiles components if this bug isn't related to Chrome Identity.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot