Chrome version: 67.0.3389.0 (Official Build) Revision 58f84d059486796cc3652797eab5eab997720cad-refs/heads/master@{#548273}(32/64-bit)
OS: Windows (7,8,8.1,10),Linux (14.04 LTS),Mac OS X(10.12.6,10.13.1,10.13.4)

What steps will reproduce the problem?
1. Launch chrome,navigate to NTP and open devtools
2. Go drag 'Styles' window to RHS so that horizontal scroll bar is seen.
3. Now drag horizontal scroll bar to RHS,observe
 
Actual: Unwanted white space is seen after dragging horizontal scroll bar to RHS  
Expected: Unwanted white space should not be seen after dragging horizontal scroll bar to RHS 

This is regression issue, broken in ‘M 65’ and below is the bisect info :
Good build: 65.0.3285.0  (Revision: 521957).
Bad build: 65.0.3286.0 (Revision: 522296).

You are probably looking for a change made after 521593 (known good), but no later than 521594 (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/14263a935f1ab00591d4636f263243838f7dab09..3b5316da83cf0a7d403759f45e53ca64930eba8b

Suspect : https://chromium.googlesource.com/chromium/src/+/3b5316da83cf0a7d403759f45e53ca64930eba8b

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

@einbinder- 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.
 
Note: Issue is also seen on M-65 Stable (build # 65.0.3325.181), M-66 Beta (build #66.0.3359.81) and M-67 Dev (build #67.0.3386.1)
 

Deleted: Actual_video.mp4 413 KB

	Actual_video.mp4 413 KB View Download

Deleted: Expected_video.mp4 295 KB

	Expected_video.mp4 295 KB View Download