Chrome Version:64.0.3251.0 (Official Build) 1ea7bc61dc1711a388b6031047506fc6e2a58051-refs/heads/master@{#512036}(32/64 bit)

OS:Windows (7,8,10),Linux (14.04 LTS),Mac(10.12.6,10.13.1).

Steps to reproduce:
1)Launch chrome and go to 'chrome://settings/content'.
2)Now press tab key until focus reaches to 'Learn more'(?) icon and press space bar key. 
3)observe.   

Actual Result:: Page gets auto scrolled after pressing space bar key.
Expected Result:Page should not get auto scrolled after pressing space bar key.

This is Regression issue broken in 'M-58' and Using the per-revision bisect providing the bisect results,
Good Build:58.0.3014.0
Bad Build:58.0.3015.0

You are probably looking for a change made after 450865 (known good), but no later than 450866 (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/2f48975e263dc630cab5dfedd6930d0fc5250579..74fa573ec3eab3ec73b1ca5b659393714a36a0a9

Suspect:https://chromium.googlesource.com/chromium/src/+/74fa573ec3eab3ec73b1ca5b659393714a36a0a9