I can't find a cause of the failures of HeadlessWebContentsTest.Focus, so assigning to you as the author.

 Issue 828041  has been merged into this issue.

btw this might be related to switching bots from Win 10 RS1 to RS2. see bug 818381. The rollout started on 3/29 and took roughly 24 hours to complete.

Actually this started failing on win7 as well, so it can't be related to the RS2 switchover.

Disable the failed test:
https://chromium-review.googlesource.com/c/chromium/src/+/992881

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/0fbc9c8e88d90196dba1469b8c173ea7f66e7524

commit 0fbc9c8e88d90196dba1469b8c173ea7f66e7524
Author: Owen Min <zmin@chromium.org>
Date: Tue Apr 03 17:34:05 2018

Disable HeadlessWebContentsTest.Focus

Disable this test as it consistently failed on Win10 and Win7.

Tbr: irisu@chromium.org
Bug: 828042
Change-Id: I5366a98999fca0911ae018a94ca479a3e6a308d9
Reviewed-on: https://chromium-review.googlesource.com/992881
Reviewed-by: Owen Min <zmin@chromium.org>
Commit-Queue: Owen Min <zmin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#547749}
[modify] https://crrev.com/0fbc9c8e88d90196dba1469b8c173ea7f66e7524/headless/lib/headless_web_contents_browsertest.cc

Removing from sheriff queue since this has an owner and test has been disabled.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/03212fef43d860b31ae8f29d360b3cdab11c2219

commit 03212fef43d860b31ae8f29d360b3cdab11c2219
Author: Johannes Henkel <johannes@google.com>
Date: Wed Apr 25 17:34:32 2018

Wait for focus before invoking document.hasFocus().

I'm not sure whether it should be this way - maybe
waiting for the page load (WaitForPageLoad) should
imply waiting for the focus as well; but this does
fix the previously flaky test. I've clarified the
name of the test also, since all this does is to
show that the two HeadlessWebContents instances
are independently focused at the same time.

R=caseq@chromium.com, eseckler@chromium.com

Bug: 828042
Change-Id: I174863b49ae525605a6aacb8750880d02fae3246
Reviewed-on: https://chromium-review.googlesource.com/1026993
Reviewed-by: Eric Seckler <eseckler@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Commit-Queue: Johannes Henkel <johannes@google.com>
Cr-Commit-Position: refs/heads/master@{#553627}
[modify] https://crrev.com/03212fef43d860b31ae8f29d360b3cdab11c2219/headless/lib/headless_web_contents_browsertest.cc
[modify] https://crrev.com/03212fef43d860b31ae8f29d360b3cdab11c2219/headless/test/headless_browser_test.cc
[modify] https://crrev.com/03212fef43d860b31ae8f29d360b3cdab11c2219/headless/test/headless_browser_test.h