The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/c6e0536bbdfb293ed22765f8892cd78e61232a03

commit c6e0536bbdfb293ed22765f8892cd78e61232a03
Author: Oskar Sundbom <ossu@chromium.org>
Date: Thu Nov 30 20:58:38 2017

Disable Mac ambient noise reduction for origin trial

The setting does not seem to be documented, but was easily found by
tracking property changes to a device and playing around in settings.

This implementation keeps a suppression count and re-enables ambient
noise reduction, if it was initially enabled, once all streams
requesting this behavior have stopped.

Bug: chromium:789152
Change-Id: I1672a44bf185beedef2caaff8f66f5c50a9aad95
Reviewed-on: https://chromium-review.googlesource.com/737873
Commit-Queue: Oskar Sundbom <ossu@chromium.org>
Reviewed-by: Jason Chase <chasej@chromium.org>
Reviewed-by: Guido Urdaneta <guidou@chromium.org>
Reviewed-by: Philip Jägenstedt <foolip@chromium.org>
Reviewed-by: Tommi <tommi@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520679}
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/content/renderer/media/media_stream_audio_processor_options.h
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/content/renderer/media/media_stream_constraints_util_audio.cc
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/content/renderer/media/media_stream_constraints_util_audio.h
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/content/renderer/media/media_stream_constraints_util_audio_unittest.cc
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/content/renderer/media/user_media_processor.cc
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/content/renderer/media/webrtc/processed_local_audio_source.cc
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/media/audio/mac/audio_low_latency_input_mac.cc
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/media/audio/mac/audio_low_latency_input_mac.h
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/media/audio/mac/audio_manager_mac.cc
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/media/audio/mac/audio_manager_mac.h
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/media/base/audio_parameters.h
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/third_party/WebKit/Source/modules/exported/WebUserMediaRequest.cpp
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/third_party/WebKit/Source/modules/mediastream/UserMediaRequest.cpp
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/third_party/WebKit/Source/modules/mediastream/UserMediaRequest.h
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/third_party/WebKit/Source/platform/runtime_enabled_features.json5
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/third_party/WebKit/public/platform/web_feature.mojom
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/third_party/WebKit/public/web/WebUserMediaRequest.h
[modify] https://crrev.com/c6e0536bbdfb293ed22765f8892cd78e61232a03/tools/metrics/histograms/enums.xml