This test also appears to be part of the network_service_interactive_ui_tests suite and fails there too. 
https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8933611326168921680/+/steps/network_service_interactive_ui_tests_on_Intel_GPU_on_Mac_on_Mac-10.14/0/stdout

Ick.

The root cause of this is that CGEventPost() can't be used on macOS 10.14 without a user prompt to enable accessibility access, and trying to use it hangs the test. Details here: <https://forums.developer.apple.com/thread/103992>

In the short term I will have this test early-out on 10.14; in the longer term I've filed 904403 about this.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/aa553244ad41e64339ae6d8deadb686ef83f6011

commit aa553244ad41e64339ae6d8deadb686ef83f6011
Author: Elly Fong-Jones <ellyjones@chromium.org>
Date: Mon Nov 12 21:01:44 2018

mac: disable GlobalCommandsApiTest GlobalCommand on 10.14

As of 10.14, the API that SendGlobalKeyEventsAndWait() uses to post global
events causes a user prompt to appear, which is an obvious non-starter in test
scenarios, so disable that test for now, and add a DCHECK in
SendGlobalKeyEventsAndWait() to ensure that it is not called on 10.14.

Bug:  892177 ,904403
Change-Id: Ida0429d7e9914942f354690ecb657803240756ae
Reviewed-on: https://chromium-review.googlesource.com/c/1331135
Reviewed-by: Scott Violet <sky@chromium.org>
Commit-Queue: Elly Fong-Jones <ellyjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#607325}
[modify] https://crrev.com/aa553244ad41e64339ae6d8deadb686ef83f6011/chrome/browser/extensions/extension_commands_global_registry_apitest.cc
[modify] https://crrev.com/aa553244ad41e64339ae6d8deadb686ef83f6011/chrome/test/base/interactive_test_utils_mac.mm