Another flake: https://ci.chromium.org/p/chromium/builders/luci.chromium.try/android-marshmallow-arm64-rel/36366

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/fe8c7d594e193f0dbdf6e3b7c970e44bee9c5c5c

commit fe8c7d594e193f0dbdf6e3b7c970e44bee9c5c5c
Author: Lily Houghton <lilyhoughton@chromium.org>
Date: Wed Jul 11 22:23:22 2018

Remove NetworkContextTest.PreconnectLessThanZero

This test is flaky on android bots, and given that its testing something that
should be explicitly unsupported (passing a negative number to a uint parameter),
I think it's worth removing for now.

Bug:  862647 
Cq-Include-Trybots: luci.chromium.try:linux_mojo
Change-Id: I316cb2cc5979aefb7335f715bd1fd2655db097b3
Reviewed-on: https://chromium-review.googlesource.com/1134206
Reviewed-by: Matt Menke <mmenke@chromium.org>
Commit-Queue: Lily Houghton <lilyhoughton@chromium.org>
Cr-Commit-Position: refs/heads/master@{#574375}
[modify] https://crrev.com/fe8c7d594e193f0dbdf6e3b7c970e44bee9c5c5c/services/network/network_context_unittest.cc