Chrome Version: 66.0.3346.0 (Official Build) Revision 21b7a819b0547b7ade4252a162cc4c98ba29f149-refs/heads/master@{#536238} 32/64-bit.
OS: Win(7,8,8.1,10), Linux(14.04 LTS).

URL: https://www.google.com/intl/en/chrome/

What steps will reproduce the problem?
1. Launch Chrome, go to above URL, open DevTools, dock it to bottom and go to Audits section.
2. Run the audit and once audit is completed click on 'Performance' or Accessibility.
3. Press "Shift + Tab" key from keyboard to bring the focus at "Accessibility/Performance" and observe.

Actual: Upper scroll bar arrow doesn't get disabled.
Expected: Upper scroll bar arrow should get disabled.

This is a regression issue, broken in M-65 series, below is manual regression range.

Good build: 65.0.3315.0 (Revision: 527553)
Bad build: 65.0.3316.0 (Revision: 527861)

You are probably looking for a change made after 527816 (known good), but no later than 527817 (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/cc2c57abc7f30b02dae2e1436458e78e7aaaa467..8b76a4f045f80c08893009a24e7b677f1bfd3ac4

Suspecting: https://chromium.googlesource.com/chromium/src/+/8b76a4f045f80c08893009a24e7b677f1bfd3ac4

@paulirish: 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 also reproducible on M-65 Beta (build # 65.0.3325.51), M-66 Dev(build # 66.0.3343.3)
2. This issue is not reproducible on Mac machines.

Kindly review the attached screen-cast for reference.

Thank you.
 

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	Actual Screenshot.png 167 KB View Download

Deleted: Expected screenshot.png 164 KB

	Expected screenshot.png 164 KB View Download

Deleted: Actual behavior.mp4 2.4 MB

	Actual behavior.mp4 2.4 MB View Download

Deleted: Expected behavior.mp4 2.0 MB

	Expected behavior.mp4 2.0 MB View Download