The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/ce9a2515fc22794d7beb2268eaae525279a0c3b1

commit ce9a2515fc22794d7beb2268eaae525279a0c3b1
Author: tommi <tommi@chromium.org>
Date: Mon Jan 16 18:35:18 2017

Refactor AudioInputController and related interfaces.

* Remove special callback code (OnData callback) for Speech and instead use the callback interface that's already supplied.
* Made methods and variables private to keep test code separate and force use of ForTesting methods.
* Removed state_ and lock_ variables from AudioInputController and removed the need for acquiring said lock in the audio callback.
* Moved inheritance of AudioInputCallback into a subclass.
* An instance of the callback subclass only exists while the callback is active. This makes the threading model clearer and allows us to avoid using locks and atomic operations.
* Made several member variable const, as their value must never change.
* Made supplying a handler_ non-optional as well as sync_writer_.  This also simplifies the code quite a bit.
* Changed the way we report UMA stats. We don't use a reference counter anymore or atomic operations. I suspect that we've been getting incorrect stats reported due to issues with how we were previously doing this (in addition to slowing down the audio path).
* Added a new UMA stat to track how often we get errors reported from the audio layer during capture.

BUG= 681150 , 681152 
CQ_INCLUDE_TRYBOTS=master.tryserver.chromium.linux:linux_optional_gpu_tests_rel;master.tryserver.chromium.mac:mac_optional_gpu_tests_rel;master.tryserver.chromium.win:win_optional_gpu_tests_rel

Review-Url: https://codereview.chromium.org/2624403002
Cr-Commit-Position: refs/heads/master@{#443925}

[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/content/browser/renderer_host/media/audio_input_renderer_host.cc
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/content/browser/renderer_host/media/audio_input_renderer_host.h
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/content/browser/renderer_host/media/audio_input_renderer_host_unittest.cc
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/content/browser/speech/speech_recognition_browsertest.cc
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/content/browser/speech/speech_recognizer_impl.cc
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/content/browser/speech/speech_recognizer_impl.h
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/content/browser/speech/speech_recognizer_impl_unittest.cc
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/media/audio/audio_input_controller.cc
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/media/audio/audio_input_controller.h
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/media/audio/audio_input_controller_unittest.cc
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/media/audio/audio_io.h
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/media/audio/test_audio_input_controller_factory.cc
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/media/audio/test_audio_input_controller_factory.h
[modify] https://crrev.com/ce9a2515fc22794d7beb2268eaae525279a0c3b1/tools/metrics/histograms/histograms.xml