Using the per-revision bisect providing the bisect results,
Good build: 57.0.2979.0 (Revision: 443120).
Bad build: 57.0.2980.0 (Revision: 443474).

You are probably looking for a change made after 443169 (known good), but no later than 443170 (first known bad).

CHANGE-LOG URL:
---------------
https://chromium.googlesource.com/chromium/src/+log/e0959faf15de830455fa90014920adec9c880bc2..cf75b7400451e8457d5b9489e27158173727ea09

From the CL above, assigning the issue to the concern owner

@einbinder: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.

Review-Url: https://codereview.chromium.org/2599623002

Note : Able to reproduce the issue in Ubuntu 14.04,Mac 10.12.2 & Win 7.

as this is recent regression marking as RB stable, please change accordingly.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/35ab0f010dd7ca82e59c9d31114e033780e4b9e6

commit 35ab0f010dd7ca82e59c9d31114e033780e4b9e6
Author: einbinder <einbinder@chromium.org>
Date: Mon Feb 06 23:54:35 2017

DevTools: Show scrollbars on a small FilteredListWidget

BUG= 688933 

Review-Url: https://codereview.chromium.org/2680543003
Cr-Commit-Position: refs/heads/master@{#448446}

[modify] https://crrev.com/35ab0f010dd7ca82e59c9d31114e033780e4b9e6/third_party/WebKit/Source/devtools/front_end/quick_open/FilteredListWidget.js
[modify] https://crrev.com/35ab0f010dd7ca82e59c9d31114e033780e4b9e6/third_party/WebKit/Source/devtools/front_end/quick_open/filteredListWidget.css
[modify] https://crrev.com/35ab0f010dd7ca82e59c9d31114e033780e4b9e6/third_party/WebKit/Source/devtools/front_end/ui/Dialog.js
[modify] https://crrev.com/35ab0f010dd7ca82e59c9d31114e033780e4b9e6/third_party/WebKit/Source/devtools/front_end/ui/GlassPane.js

einbinder@ If possible, please merge your change to M57 branch 2987.

A friendly reminder that M57 Stable is launch is coming soon! Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and get it merged into the release branch ASAP so it gets enough baking time in Beta (before Stable promotion). Thank you!

Rechecked the issue on canary version 58.0.3012.0 on Windows 10, Ubuntu 14.04, MAC 10.12.2, fix is working as intended. Able to scroll the page and scroll bar is displayed.

Adding TE-Verified labels.

A friendly reminder that M57 Stable is launch is coming VERY soon! Your bug is labelled as Stable ReleaseBlock, pls make sure to land the fix and get it merged into the release branch (2987) ASAP so it gets enough baking time in Beta (before Stable promotion). Thank you!

URGENT - PTAL ASAP.

We're getting VERY close to M57 Stable promotion. And 
this issue is marked as M57 stable release blocker. Pls make sure to land the fix and get it merged into the release branch ASAP so it gets enough baking time in Beta (before Stable promotion).

Know that this issue shouldn't block the release?  Remove the ReleaseBlock-Stable label or move to M58.

Thank you.

einbinder@, please request a merge to M57 if CL listed at #3 is a safe merge to M57. Thank you.

Doesn't seem important enough to merge.

[Auto-generated comment by a script] We noticed that this issue is targeted for M-57; it appears the fix may have landed after branch point, meaning a merge might be required. Please confirm if a merge is required here - if so add Merge-Request-57 label, otherwise remove Merge-TBD label. Thanks.

Per comment #10, M57 merge is not needed.