The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/365dc9f4b3788bce7c1159e3fbaac112b02dd556

commit 365dc9f4b3788bce7c1159e3fbaac112b02dd556
Author: Xiangjun Zhang <xjz@chromium.org>
Date: Fri Jun 08 19:28:35 2018

Allow AudioDeviceThread to be created with NORMAL thread priority.

Currently the media::AudioDeviceThread is always created with
REALTIME_AUDIO thread priority. However, when calling from the new
Mirroring Service running in a sandboxed utility process (coming in
future CLs), the REALTIME_AUDIO priority is not allowed due to sandbox
syscall restrictions. Also, since the input audio data is buffered,
there is no need to use REALTIME_AUDIO thread for mirroring.

This CL allows media::AudioDeviceThread to be created with requested
thread priority. There should be no change to existing behavior.

Bug:  850352 
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: Id9e724b230e14c269f262c1c4c7e2b15ac08a57d
Reviewed-on: https://chromium-review.googlesource.com/1090226
Commit-Queue: Xiangjun Zhang <xjz@chromium.org>
Reviewed-by: Olga Sharonova <olka@chromium.org>
Reviewed-by: Yuri Wiitala <miu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#565713}
[modify] https://crrev.com/365dc9f4b3788bce7c1159e3fbaac112b02dd556/content/renderer/media/audio/audio_device_factory.cc
[modify] https://crrev.com/365dc9f4b3788bce7c1159e3fbaac112b02dd556/media/audio/audio_device_thread.cc
[modify] https://crrev.com/365dc9f4b3788bce7c1159e3fbaac112b02dd556/media/audio/audio_device_thread.h
[modify] https://crrev.com/365dc9f4b3788bce7c1159e3fbaac112b02dd556/media/audio/audio_input_device.cc
[modify] https://crrev.com/365dc9f4b3788bce7c1159e3fbaac112b02dd556/media/audio/audio_input_device.h
[modify] https://crrev.com/365dc9f4b3788bce7c1159e3fbaac112b02dd556/media/audio/audio_input_device_unittest.cc
[modify] https://crrev.com/365dc9f4b3788bce7c1159e3fbaac112b02dd556/media/audio/audio_output_device.cc
[modify] https://crrev.com/365dc9f4b3788bce7c1159e3fbaac112b02dd556/services/audio/public/cpp/device_factory.cc