Add a virtual beamforming audio device on ChromeOS.

media/audio/cras/audio_manager_cras.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_AUDIO_CRAS_AUDIO_MANAGER_CRAS_H_
 #define MEDIA_AUDIO_CRAS_AUDIO_MANAGER_CRAS_H_
 
 #include <cras_types.h>
 
 #include <string>
@@ skipping 43 matching lines @@
  private:
   // Called by MakeLinearOutputStream and MakeLowLatencyOutputStream.
   AudioOutputStream* MakeOutputStream(const AudioParameters& params);
 
   // Called by MakeLinearInputStream and MakeLowLatencyInputStream.
   AudioInputStream* MakeInputStream(const AudioParameters& params,
                                     const std::string& device_id);
 
   bool has_keyboard_mic_;
 
+  // Holds the name and ID of a virtual beamforming device if the machine
+  // indicates it has a mic array by providing a mic positions field.
+  const AudioDeviceName beamforming_device_name_;

[Henrik Grunell, 2015/08/27 08:38:18]

Why is it restricted to only the default device?

Does it make sense to abstract a device, instead of hard coding the virtual one
here?

[ajm, 2015/08/28 07:36:13]

AudioManagerCras only exposes a single device called "Default" today. Not sure
exactly what you mean by "abstract a device".

[aluebs-chromium, 2015/08/28 19:14:30]

Do these really need to be part of the state of this class? Or can't you just
query or concatenate them when needed?

[ajm, 2015/08/28 23:38:31]

They're immutable, so we're not expanding the "state-space" if you will. I don't
mind computing beamforming_device_name_ on demand, but I'd prefer to leave
mic_positions_ as a member to avoid the unknown complexity of querying CRAS for
the device list.

[aluebs-chromium, 2015/08/29 00:00:26]

Agreed.

+  // Stores the mic positions field from the device.

[Henrik Grunell, 2015/08/27 08:38:18]

Nit: Empty line before comment.

+  const std::string mic_positions_;
+
   DISALLOW_COPY_AND_ASSIGN(AudioManagerCras);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_CRAS_AUDIO_MANAGER_CRAS_H_