Thanks. Please go ahead to disable it. I will take a look first thing tomorrow.

so i clicked on those flaky runs (black and grey boxes), I don't see any failed runs with NetworkConnectionTracker/0 timing out in the build outputs. 

Not very familiar with the flakiness dashboard, Could you link me to an example?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/3cdc518d8af59b78b23edd94862a839dde3216a4

commit 3cdc518d8af59b78b23edd94862a839dde3216a4
Author: Scott Violet <sky@chromium.org>
Date: Wed Nov 08 01:56:36 2017

Disables NetworkConnectionTrackerBrowserTest.NetworkConnectionTracker/0

It hits the timeout on numerous builders.

BUG= 782491 
TEST=test only change.
TBR=xunjieli@chromium.org

Change-Id: I5fece7cda90323e2714d7d550665a21a1cea52ab
Reviewed-on: https://chromium-review.googlesource.com/757906
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#514705}
[modify] https://crrev.com/3cdc518d8af59b78b23edd94862a839dde3216a4/chrome/browser/net/network_connection_tracker_browsertest.cc

I think you're right. I think this is the failure I saw: https://logs.chromium.org/v/?s=chromium%2Fbb%2Fchromium.linux%2FLinux_Tests%2F64301%2F%2B%2Frecipes%2Fsteps%2Fsite_per_process_browser_tests%2F0%2Flogs%2FNetworkConnectionTrackerBrowserTest.NetworkConnectionTracker__x2f_0%2F0 , which is on the site per process bot. None-the-less the solid black squares show timeouts on other bots, so this test does frequently timeout, but not so often 4 times in a row.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/da36d47f7b78f5a3dec653a14f19d1fd799b29dc

commit da36d47f7b78f5a3dec653a14f19d1fd799b29dc
Author: Helen Li <xunjieli@chromium.org>
Date: Fri Nov 10 17:13:01 2017

fix NetworkConnectionTrackerBrowserTest flake and re-enable

When NetworkService is in process, the SimulateNetworkChange() can be called
before NetworkService is started up. If that happens, the
NetworkChangeManager will never receive the broadcast and hence the test
will hang waiting for the notification which never arrives.

The test flake can be reproduced locally with a release build.

Bug:  782491 
Change-Id: I8ed930b7a8f618ebf5e9aff6f23a48cb2f20ebce
Reviewed-on: https://chromium-review.googlesource.com/763928
Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Helen Li <xunjieli@chromium.org>
Cr-Commit-Position: refs/heads/master@{#515577}
[modify] https://crrev.com/da36d47f7b78f5a3dec653a14f19d1fd799b29dc/chrome/browser/net/network_connection_tracker_browsertest.cc

Thanks sky@ for filing the bug!