The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5e8d8448f94a844159946daa7d58cdf4305abb91

commit 5e8d8448f94a844159946daa7d58cdf4305abb91
Author: Guido Urdaneta <guidou@chromium.org>
Date: Tue May 15 13:41:17 2018

Remove the dependency of CoreAudioUtilMac from AudioManager.

The dependency was used to DCHECK that Core Audio functions run on
the same task runner as the AudioManager.
However, with the new audio service running on a separate process, the
device monitor on the browser process fails the DCHECKs because there
is no AudioManager.

This CL is to be followed by a CL that moves monitoring to the audio
service. Still, such monitoring need not depend on the AudioManager,
so the removal of this dependency holds in that case as well.

Bug:  843106 
Cq-Include-Trybots: luci.chromium.try:android_optional_gpu_tests_rel;luci.chromium.try:linux_optional_gpu_tests_rel;luci.chromium.try:mac_optional_gpu_tests_rel;luci.chromium.try:win_optional_gpu_tests_rel
Change-Id: I988b3bf47219556117ed0ea7545281237db5bdee
Reviewed-on: https://chromium-review.googlesource.com/1059653
Commit-Queue: Guido Urdaneta <guidou@chromium.org>
Commit-Queue: Olga Sharonova <olka@chromium.org>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Cr-Commit-Position: refs/heads/master@{#558688}
[modify] https://crrev.com/5e8d8448f94a844159946daa7d58cdf4305abb91/media/audio/mac/core_audio_util_mac.cc