Using the per-revision bisect providing the bisect results,
Good build: 59.0.3063.0 (Revision: 461928).
Bad build : 59.0.3064.0 (Revision: 462305).

You are probably looking for a change made after 462303 (known good), but no later than 462304 (first known bad).
CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/c198feadcc54ea92134df2dc3a5f4f390fcd9493..9b3c62205a0b13f99c59792b834f485b825e2cb8


@dpapad: 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.
Thank You.

So, I think I found the issue. Now that the outer container div has a tabindex of -1, it is focusable. When the user clicks on "Show home button" div, the focus travels to the outer container, because the "Show home button" div itself is not focusable.

A possible fix is at https://codereview.chromium.org/2798223006, but we would need to deploy this to all our clickable div "buttons". I am not sure if this is worth it, or whether we should simply revert the original CL (and mark the original bug as WAI,  crbug.com/707106 ).

I uploaded a better approach in the same CL mentioned above. Removing the tabindex attribute from the container after it is blurred seems to address this regression, without creating any other unwanted sideeffects.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3a2e5144ab506f18ae56a2bbe4eb23f43ddd5dcd

commit 3a2e5144ab506f18ae56a2bbe4eb23f43ddd5dcd
Author: dpapad <dpapad@chromium.org>
Date: Sat Apr 08 03:07:54 2017

MD Settings: Remove tabindex from container after it is blurred.

Clicking on non-focusable elements (for example the "Show home button" row) would
transfer the focus to the container accidentally, now that it has a tabindex. Removing
the tabindex from the container as soon as the container is blurred addresses the problem.

BUG= 709359 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2798223006
Cr-Commit-Position: refs/heads/master@{#463118}

[modify] https://crrev.com/3a2e5144ab506f18ae56a2bbe4eb23f43ddd5dcd/chrome/browser/resources/settings/settings_ui/settings_ui.html
[modify] https://crrev.com/3a2e5144ab506f18ae56a2bbe4eb23f43ddd5dcd/chrome/browser/resources/settings/settings_ui/settings_ui.js