The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/20f35d2a26b8778e8a16b724442802768195b8ee

commit 20f35d2a26b8778e8a16b724442802768195b8ee
Author: Elly Fong-Jones <ellyjones@chromium.org>
Date: Thu Feb 22 14:36:53 2018

extensions: disable shell operations in DownloadsShowDefaultFolder test

On Mac, this test opens a Finder window which remains open after the test
ends; suppress actually opening the window. Failing to do this causes
Finder windows to accumulate over time on Mac test bots.

Bug:  814356 
Change-Id: I276b97ede5061faa354785fd7f96f308135873a4
Reviewed-on: https://chromium-review.googlesource.com/929701
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#538430}
[modify] https://crrev.com/20f35d2a26b8778e8a16b724442802768195b8ee/chrome/browser/extensions/api/downloads/downloads_api_browsertest.cc