Narrow Bisect info : 

https://chromium.googlesource.com/chromium/src/+log/b3d7ea8cb1769efdcc5ba3a3a8a359f0a42366a0..f496b3ba7952691970a00e8f1a4d0bcd0de47ce0?pretty=fuller&n=10000

Suspecting: r553382

@dpapad: Could you please help to reassign if your change is not the cause for this change.
Note:
1.Error shown while doing with new-script(RuntimeError: We don't have enough builds to bisect. revlist: [])
2.Unable to provide bisect using per-revision script,Hence providing bisect with old script.
3.Issue is also  Mac(10.12.6,10.13.1,10.13.5).
4.chrome://extension page has several focus issues on buttons example.load packed extension window's button.

Thank You!

 

As this is a recent regression adding release blocker label for this issue.Please reduce priority or remove if not the case.

Thank You!

I am only able to reproduce this on Mac, but not on Linux (have not tried Windows). Investigating...

Candidate fix https://chromium-review.googlesource.com/c/chromium/src/+/1035785.

 Issue 837875  has been merged into this issue.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/598ee78d952110ab83d5f7d33f91e92c7fc06ef7

commit 598ee78d952110ab83d5f7d33f91e92c7fc06ef7
Author: dpapad <dpapad@chromium.org>
Date: Tue May 01 00:37:16 2018

WebUI MD Refresh: Fix focused state on Extensions page.

It turns out that CSS mixins inheritance and precedence is more fragile than normal
CSS classes. The order of style includes affects the precedence, which caused the
styling to look correct on Settings, but incorrect on Extensions
(happens only with optimize_webui=true).

Bug:  837140 
Cq-Include-Trybots: master.tryserver.chromium.linux:closure_compilation
Change-Id: I22b592315964c3101d25c68dd5f5f1c29d75b347
Reviewed-on: https://chromium-review.googlesource.com/1035785
Reviewed-by: Scott Chen <scottchen@chromium.org>
Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
Cr-Commit-Position: refs/heads/master@{#554943}
[modify] https://crrev.com/598ee78d952110ab83d5f7d33f91e92c7fc06ef7/ui/webui/resources/cr_elements/paper_button_style_css.html

Update : 
Retested above issue on Windows (7,8,8.1,10) Linux(14.04 LTS) and Mac(10.12.6,10.13.1,10.13.5) OS using latest Canary #68.0.3417.0 and issue is fixed.Focus is observed on 'Details' and 'Remove' button .Kindly review the attached screen-cast.

Thank you!

Deleted: Canary_Behaviour#68.0.3417.0.mov 4.3 MB

	Canary_Behaviour#68.0.3417.0.mov 4.3 MB View Download