Flaky on mac. Some of the runs timeout, some fail.

On https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Mac10.11%20(dbg)/16674 we have:
--- /b/s/w/iomq3M1u/layout-test-results/webexposed/global-interface-listing-expected.txt
+++ /b/s/w/iomq3M1u/layout-test-results/webexposed/global-interface-listing-actual.txt
@@ -4651,6 +4651,7 @@
     getter userAgent
     getter vendor
     getter vendorSub
+    getter webdriver
     getter webkitPersistentStorage
     getter webkitTemporaryStorage
     getter xr

+fmeawad@ as an active developer of WebDriver.

Are you recently switching AutomationControlled runtime-enabled flag?  Or changing something that affects |webdriver| exposure?  If so, could you update the expectation file?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/945a34793bc784acc54847963a7707c86c6026e2

commit 945a34793bc784acc54847963a7707c86c6026e2
Author: Alexander Potapenko <glider@google.com>
Date: Thu Jun 07 14:21:09 2018

Sheriffing on 2018-06-07: added test expectations

Bug:  831496 
Bug:  850395 
Bug: 850358
Bug: 850206
Bug:  849978 
Change-Id: Iff076718738bb365551d6dbc4e39edbb5bf3ffda

TBR=nhiroki@chromium.org

Change-Id: Iff076718738bb365551d6dbc4e39edbb5bf3ffda
Reviewed-on: https://chromium-review.googlesource.com/1090837
Reviewed-by: Alexander Potapenko <glider@chromium.org>
Commit-Queue: Alexander Potapenko <glider@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565257}
[modify] https://crrev.com/945a34793bc784acc54847963a7707c86c6026e2/third_party/WebKit/LayoutTests/TestExpectations

Changing owner to Johnathan who is working on Webdriver.

It seems that the webdriver object is getting added to the Navigator object, I am not sure if this is caused by a testing flag or something else?

Hi Jon, any update on this bug?

As in bug 862161, it's important that "virtual/stable/webexposed/global-interface-listing.html" is always being run. That test has been turned back on. Until we come up with a more permanent solution, I'm hoping to avoid any flakiness that would cause it to be turned off.

The navigator.webdriver object was added due to  issue #723900 . It is exposed whenever --enable-automation or --headless flag is found on the Chrome command line. Not sure why it's causing flakiness. It's supposed to be quite deterministic for any given Chrome command line.

Detected 3 new flakes for test/step "virtual/stable/webexposed/global-interface-listing.html". To see the actual flakes, please visit https://chromium-try-flakes.appspot.com/all_flake_occurrences?key=ahVzfmNocm9taXVtLXRyeS1mbGFrZXNyQgsSBUZsYWtlIjd2aXJ0dWFsL3N0YWJsZS93ZWJleHBvc2VkL2dsb2JhbC1pbnRlcmZhY2UtbGlzdGluZy5odG1sDA. This message was posted automatically by the chromium-try-flakes app. Since flakiness is ongoing, the issue was moved back into Sheriff Bug Queue (unless already there).