The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/df82bdd1fae72b438391543ef08b5e1cfa39453e

commit df82bdd1fae72b438391543ef08b5e1cfa39453e
Author: Marina Ciocea <marinaciocea@chromium.org>
Date: Tue Jun 12 16:09:16 2018

Add OutputDevice to audio service.

Add audio::OutputDevice to be used by audio service clients different than renderers,
e.g. sounds manager, assistant.

Notes:
- StreamFactory::CreateOutputStream now accepts optional observer and log ptr, because non-renderer
  output device clients don't need to use them.
- Moved AudioThreadCallback out to media::AudioOutputDevice to be reused by audio::OutputDevice.
- AudioOutputDeviceThreadCallback is tested in media:: and audio:: output device implementations.

Audio service design doc: https://docs.google.com/document/d/1s_Fd1WRDdpb5n6C2MSJjeC3fis6hULZwfKMeDd4K5tI/edit?usp=sharing

Bug:  850923 
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: I582a2445445c9937860906c92452915015239334
Reviewed-on: https://chromium-review.googlesource.com/1095184
Commit-Queue: Marina Ciocea <marinaciocea@chromium.org>
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Max Morin <maxmorin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#566448}
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/media/audio/BUILD.gn
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/media/audio/audio_output_device.cc
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/media/audio/audio_output_device.h
[add] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/media/audio/audio_output_device_thread_callback.cc
[add] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/media/audio/audio_output_device_thread_callback.h
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/BUILD.gn
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/output_stream.cc
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/output_stream_unittest.cc
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/public/cpp/BUILD.gn
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/public/cpp/input_ipc.h
[add] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/public/cpp/output_device.cc
[add] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/public/cpp/output_device.h
[add] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/public/cpp/output_device_unittest.cc
[modify] https://crrev.com/df82bdd1fae72b438391543ef08b5e1cfa39453e/services/audio/public/mojom/stream_factory.mojom