You are probably looking for a change made after 608012 (known good), but no later than 608013 (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/2f231722674efc952111bde4ba7fc8921c165c29..b64d0a8c04db08eaa81502868a5802d660030842

Suspecting: https://chromium.googlesource.com/chromium/src/+/b64d0a8c04db08eaa81502868a5802d660030842

@hugoh: Could you please check whether this is caused with respect to your change, if not please help us in assigning it to the right owner.

Thank You..!

marking as RBS, please change if required

My feature, KeyboardFocusableScrollers, had already been disabled in 72.0.3623.0.

I redid the bisect with --disable-blink-features=KeyboardFocusableScrollers. Bisect range is:
https://chromium.googlesource.com/chromium/src/+log/fc50c1477673ff62ae6243ab30de31fd4b430c01..42c0440fcedf33a9eae9d8049ba2900d10bdb5be
so this is likely due to https://chromium-review.googlesource.com/c/chromium/src/+/1343197, which was an attempt to fix a different settings page regression due to the focusable scrollers.

This bug seems similar to the Print Preview bug that surfaced due to a similar fix attempt, see https://crbug.com/907378. In that case I reverted the CL, since we decided to turn KeyboardFocusableScrollers off for now. We should probably do the same here.

@rbpotter: Thanks for the investigation. I agree that we should revert that CL for now as well.

@hugoh: IIUC, the tab focusable vs click focusable issue is what you are referring to at https://bugs.chromium.org/p/chromium/issues/detail?id=908809#c3 ?

@dpapad, what I mean in  Issue 908809 #c3 is that I will probably need to land a rewrite of KeyboardFocusableScrollers. Current KeyboardFocusableScrollers unintentionally affected click-focusing ( Issue 908809 ). Perhaps that's the root cause to some of the WebUI issues (Issue 907284) we've seen.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/760f1f815c71b362e60a40ee421c10a6372e040b

commit 760f1f815c71b362e60a40ee421c10a6372e040b
Author: Rebekah Potter <rbpotter@chromium.org>
Date: Wed Nov 28 22:39:45 2018

Revert "Settings WebUI: Add tabindex -1 in scrolling container to prevent tabstop."

This reverts commit 42c0440fcedf33a9eae9d8049ba2900d10bdb5be.

Reason for revert: This causes https://crbug.com/908775, and the
Blink changes that were the reason for the change have been
rolled back for now.

Original change's description:
> Settings WebUI: Add tabindex -1 in scrolling container to prevent tabstop.
>
> This is necessary because of recent Blink changes at r608013.
>
> Bug: 905999
> Change-Id: I111e3631e4d832afb48a4161552fc27a1bbb9630
> Reviewed-on: https://chromium-review.googlesource.com/c/1343197
> Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
> Commit-Queue: Demetrios Papadopoulos <dpapad@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#609546}

TBR=dpapad@chromium.org,rbpotter@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 905999, 908775
Change-Id: Ie14d8cbea36dcb91d03e8e7ab7b2fdd5010fcc10
Reviewed-on: https://chromium-review.googlesource.com/c/1354235
Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611906}
[modify] https://crrev.com/760f1f815c71b362e60a40ee421c10a6372e040b/chrome/browser/resources/settings/settings_ui/settings_ui.html

Update:
Rechecked this issue on Windows(7,8,8.1,10), Mac(10.13.1, 10.13.6, 10.14.2) and Linux(14.04) machines using latest Canary #72.0.3625.0 and issue is fixed. Hence adding TE-Verified labels.

please refer the attached screen-cast for reference.

Thank you.

Deleted: Fixed behavior.mp4 547 KB

	Fixed behavior.mp4 547 KB View Download

Removing RBS, but keeping this open to track fixes needed before relanding the original Blink change.