Using the per-revision bisect providing the bisect results,
Good build: 56.0.2920.0 (Revision: 432057).
Bad build: 56.0.2992.0 (Revision: 432511).

You are probably looking for a change made after 432277 (known good), but no later than 432278 (first known bad).
CHANGELOG URL:
  https://chromium.googlesource.com/chromium/src/+log/5ce3e1f8fef0f96ae28a09ac0aba2dc49802f9ee..aaffafea03c011414d72d7997bdd83d2f4853de0

@tsergeant -- 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.

Note : Issue is not seen on Linux and Windows OS.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/572f871f139ed9a514b69707a7e25345fff0de2b

commit 572f871f139ed9a514b69707a7e25345fff0de2b
Author: tsergeant <tsergeant@chromium.org>
Date: Fri Nov 18 04:37:18 2016

MD WebUI: Fix minor rendering problems in <cr-toolbar>

In crrev.com/589355, the <cr-toolbar> element moved from using
paper-input to a native <input> element. This CL fixes two minor issues
that came about as a result of this change:

* Fix font rendering issues on macOS so that text is the right size and
  antialiased correctly
* Ensure that right clicking shows the <input> context menu
* Prevent label text from wrapping during animations

BUG= 589355 , 666183 , 666180 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2502413003
Cr-Commit-Position: refs/heads/master@{#433107}

[modify] https://crrev.com/572f871f139ed9a514b69707a7e25345fff0de2b/chrome/browser/resources/md_downloads/vulcanized.html
[modify] https://crrev.com/572f871f139ed9a514b69707a7e25345fff0de2b/chrome/browser/resources/md_history/app.vulcanized.html
[modify] https://crrev.com/572f871f139ed9a514b69707a7e25345fff0de2b/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8832b0411ba993c9a62ff52044767a5885d758ab

commit 8832b0411ba993c9a62ff52044767a5885d758ab
Author: Tim Sergeant <tsergeant@chromium.org>
Date: Sun Nov 20 23:23:55 2016

MD WebUI: Fix minor rendering problems in <cr-toolbar>

In crrev.com/589355, the <cr-toolbar> element moved from using
paper-input to a native <input> element. This CL fixes two minor issues
that came about as a result of this change:

* Fix font rendering issues on macOS so that text is the right size and
  antialiased correctly
* Ensure that right clicking shows the <input> context menu
* Prevent label text from wrapping during animations

BUG= 589355 , 666183 , 666180 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:closure_compilation

Review-Url: https://codereview.chromium.org/2502413003
Cr-Commit-Position: refs/heads/master@{#433107}
(cherry picked from commit 572f871f139ed9a514b69707a7e25345fff0de2b)

Review URL: https://codereview.chromium.org/2520623004 .

Cr-Commit-Position: refs/branch-heads/2924@{#15}
Cr-Branched-From: 3a87aecc31cd1ffe751dd72c04e5a96a1fc8108a-refs/heads/master@{#433059}

[modify] https://crrev.com/8832b0411ba993c9a62ff52044767a5885d758ab/chrome/browser/resources/md_downloads/vulcanized.html
[modify] https://crrev.com/8832b0411ba993c9a62ff52044767a5885d758ab/chrome/browser/resources/md_history/app.vulcanized.html
[modify] https://crrev.com/8832b0411ba993c9a62ff52044767a5885d758ab/ui/webui/resources/cr_elements/cr_toolbar/cr_toolbar_search_field.html