Chrome Version:53.0.2785.21 (Official Build) Revision 3ec5ccd4e93a73da783addab676596886de56d27-refs/branch-heads/2785@{#212} (32/64-bit)
OS:Windows(7,8,10),Linux(14.04 LTS)

Test URL: https://www.google.com/intl/en/mail/help/about.html

Steps:
1.Launch chrome,navigate to above URL and open Devtools
2.Click on toggle device mode,set resolution to be 400x831 and observe.

Actual:Unwanted scrollbar is observed after clicking on device mode.
Expected:Single Scrollbar should be seen after clicking on device mode.

This is a regression issue, broken in M-52 series, below is bisect info.

Good build:52.0.2730.0
Bad build: 52.0.2733.0

Narrow bisect: 
https://chromium.googlesource.com/chromium/src/+log/26a0f04b865ed320aea7cc1e586b80de8d396753..d6fdbb084660f06781c6932cc44b09aca20dfa29?pretty=fuller&n=100

Suspecting: r392554?

Please re-assign if your change is not cause of this issue.
Note: This issue is not seen on Mac OS.
 

Deleted: Actual_Result.mp4 1.2 MB

	Actual_Result.mp4 1.2 MB View Download

Deleted: Expected_Result.mp4 572 KB

	Expected_Result.mp4 572 KB View Download