Seems related to  issue 599787  - maybe a dupe?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/bfa0f79fa5d0bb488214fb88eb832c6105591441

commit bfa0f79fa5d0bb488214fb88eb832c6105591441
Author: sebsg <sebsg@chromium.org>
Date: Thu May 11 16:26:16 2017

[Sheriff] Disable UpdateIncognitoEnableDisable on CrOS - flaky.

BUG=721391

TBR=maxbogue@chromium.org

Review-Url: https://codereview.chromium.org/2882453002
Cr-Commit-Position: refs/heads/master@{#470971}

[modify] https://crrev.com/bfa0f79fa5d0bb488214fb88eb832c6105591441/chrome/browser/sync/test/integration/two_client_app_list_sync_test.cc

Looks like this fell through the cracks, should be investigated/fixed. May want to just re-enable and see if it still flakes, this was a long time ago.

This issue has been Available for over a year. If it's no longer important or seems unlikely to be fixed, please consider closing it out. If it is important, please re-triage the issue.

Sorry for the inconvenience if the bug really should have been left as Available.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot