I'm not sure I quite get this. The graph seems to imply that the "pass rate" was consistently 0% before the "culprit" CL, and is hovering around 80% afterwards. Assuming a "pass rate of 0%" means consistent failure, this seems like an improvement to me?

Also (before anyone does anything hastily:) I would like to point out that the alleged culprit is a _revert_ CL, and it has actually been reverted again by commit #587759 (https://chromium-review.googlesource.com/c/chromium/src/+/1197402). Which BTW did not seem to have affected the pass rate.

Try-flakes link: https://chromium-try-flakes.appspot.com/all_flake_occurrences?key=ahVzfmNocm9taXVtLXRyeS1mbGFrZXNyTwsSBUZsYWtlIkRDaHJvbWVOZXdXaW5kb3dDbGllbnRCcm93c2VyVGVzdC5OZXdXaW5kb3dGb3JBY3RpdmVXaW5kb3dQcm9maWxlVGVzdAw

https://chromium-review.googlesource.com/c/chromium/src/+/1231157 to disable test since we don't have a clear culprit. The other test in the suite seems to be fine.

I'm taking this off the sheriff queue based on https://chromium-review.googlesource.com/c/chromium/src/+/1231157#message-6b992618f2b00a4a68d0fa21580bad993063e765

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c4baffd7f89150e34fbf41740adcd7cbd7b2157d

commit c4baffd7f89150e34fbf41740adcd7cbd7b2157d
Author: Ryan Cui <rcui@chromium.org>
Date: Tue Sep 18 23:15:46 2018

[SingleProcessMash] Disable ChromeNewWindowClientBrowserTest.NewWindowForActiveWindowProfileTest

Seeing flaky failures for the test on the MSan bot.

Bug: 884118
Change-Id: Id2773b731b054bbecb02fd9bca8f7c00d2f5f447
Reviewed-on: https://chromium-review.googlesource.com/1232193
Reviewed-by: Asanka Herath <asanka@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Ryan Cui <rcui@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592249}
[modify] https://crrev.com/c4baffd7f89150e34fbf41740adcd7cbd7b2157d/testing/buildbot/filters/chromeos.single_process_mash.browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/dddff33a1af25c42b8cd1627ef8a3b3a6898d28c

commit dddff33a1af25c42b8cd1627ef8a3b3a6898d28c
Author: Ryan Cui <rcui@chromium.org>
Date: Wed Sep 19 22:04:31 2018

Revert "[SingleProcessMash] Disable ChromeNewWindowClientBrowserTest.NewWindowForActiveWindowProfileTest"

This reverts commit c4baffd7f89150e34fbf41740adcd7cbd7b2157d.

Reason for revert: Disabling the test in the source instead (https://chromium-review.googlesource.com/c/chromium/src/+/1231157) since it doesn't just fail in single_process_mash_browser_tests.

Original change's description:
> [SingleProcessMash] Disable ChromeNewWindowClientBrowserTest.NewWindowForActiveWindowProfileTest
>
> Seeing flaky failures for the test on the MSan bot.
>
> Bug: 884118
> Change-Id: Id2773b731b054bbecb02fd9bca8f7c00d2f5f447
> Reviewed-on: https://chromium-review.googlesource.com/1232193
> Reviewed-by: Asanka Herath <asanka@chromium.org>
> Reviewed-by: Scott Violet <sky@chromium.org>
> Commit-Queue: Ryan Cui <rcui@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#592249}

TBR=sky@chromium.org,asanka@chromium.org,rcui@chromium.org

Change-Id: Idf34799791c2da559f0e4e3909d0aa54c482cd97
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 884118
Reviewed-on: https://chromium-review.googlesource.com/1234264
Commit-Queue: Ryan Cui <rcui@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592566}
[modify] https://crrev.com/dddff33a1af25c42b8cd1627ef8a3b3a6898d28c/testing/buildbot/filters/chromeos.single_process_mash.browser_tests.filter

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ffc676ac0c18e43ababffd87ad06463a419494a6

commit ffc676ac0c18e43ababffd87ad06463a419494a6
Author: Asanka Herath <asanka@chromium.org>
Date: Wed Sep 19 23:27:47 2018

Disable ChromeNewWindowClientBrowserTest.NewWindowForActiveWindowProfileTest

Test is flaky.

Bug: 884118
Change-Id: I0cd103f1340536eee94a28cafe579cf186804840
Reviewed-on: https://chromium-review.googlesource.com/1231157
Reviewed-by: Asanka Herath <asanka@chromium.org>
Reviewed-by: Tommy Li <tommycli@chromium.org>
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Asanka Herath <asanka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#592604}
[modify] https://crrev.com/ffc676ac0c18e43ababffd87ad06463a419494a6/chrome/browser/ui/ash/chrome_new_window_client_browsertest.cc