Chrome version: 65.0.3315.4 (Official Build) f9677678abcb81cc8c22c4a489c5d7170e87cc9a-refs/branch-heads/3315@{#5}(32/64-bit)
OS: Win(7,8.1,10).

URL : https://chrome.google.com/webstore/search/palette%20creator?utm_source=chrome-ntp-icon

What steps will reproduce the problem?
1.Launch chrome and Navigate to above URL and download the extension.
2.Click on extension in omnibox and click on options and observe.

Actual Result: Unwanted expansion of extension overlay is seen.
Expected Result: Extension overlay should not expand while opening.

This is Regression Issue broken in M-63 and using the per-revision bisect providing the bisect results,
Good Build: 63.0.3223.0((Revision: 503965)
Bad Build: 63.0.3225.0((Revision: 504540)

Kindly refer the Bisect-info:

You are probably looking for a change made after 504421 (known good), but no later than 504422 (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/1b62135c07abbd0fb531b03fddb3c2114cb06698..3131414035a033d1fb624913474dbdac04158198

Suspect : https://chromium.googlesource.com/chromium/src/+/3131414035a033d1fb624913474dbdac04158198

@ lfg : 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.

Note: 
1. This issue is not seen on Mac and Linux OS.
2. This issue is also seen on M-63 Stable (build #63.0.3239.132),M64 Beta(build #64.0.3282.71)  

Thank You
 

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