Add a virtual beamforming audio device on ChromeOS.

media/audio/audio_parameters.h

Index: media/audio/audio_parameters.h
diff --git a/media/audio/audio_parameters.h b/media/audio/audio_parameters.h
index 3820d8cc3c91de2f3f7168d58074d2b25f8a4072..c6638e7741c9d5fcc89b00ffdecdb6705ea55973 100644
--- a/media/audio/audio_parameters.h
+++ b/media/audio/audio_parameters.h
@@ -9,6 +9,7 @@
 
 #include "base/basictypes.h"
 #include "base/time/time.h"
+#include "media/audio/point.h"
 #include "media/base/channel_layout.h"
 #include "media/base/media_export.h"
 
@@ -57,15 +58,25 @@ class MEDIA_EXPORT AudioParameters {
   };
 
   AudioParameters();
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  int sample_rate, int bits_per_sample,
-                  int frames_per_buffer);
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  int sample_rate, int bits_per_sample,
-                  int frames_per_buffer, int effects);
-  AudioParameters(Format format, ChannelLayout channel_layout,
-                  int channels, int sample_rate, int bits_per_sample,
-                  int frames_per_buffer, int effects);
+  AudioParameters(
+      Format format,
+      ChannelLayout channel_layout,
+      int sample_rate,
+      int bits_per_sample,
+      int frames_per_buffer,
+      const std::vector<Point>& mic_positions = std::vector<Point>(),
+      int effects = NO_EFFECTS);
+  AudioParameters(
+      Format format,
+      int channels,
+      ChannelLayout channel_layout,
+      int sample_rate,
+      int bits_per_sample,
+      int frames_per_buffer,
+      const std::vector<Point>& mic_positions = std::vector<Point>(),
+      int effects = NO_EFFECTS);
+
+  ~AudioParameters();
 
   void Reset(Format format, ChannelLayout channel_layout,
              int channels, int sample_rate, int bits_per_sample,
@@ -102,6 +113,7 @@ class MEDIA_EXPORT AudioParameters {
   int frames_per_buffer() const { return frames_per_buffer_; }
   int channels() const { return channels_; }
   int effects() const { return effects_; }
+  const std::vector<Point>& mic_positions() const { return mic_positions_; }
 
  private:
   // These members are mutable to support entire struct assignment. They should
@@ -114,6 +126,20 @@ class MEDIA_EXPORT AudioParameters {
 
   int channels_;                  // Number of channels. Value set based on
                                   // |channel_layout|.
+
+  // Microphone positions using Cartesian coordinates:
+  // x: the horizontal dimension, with positive to the right from the camera's
+  //    perspective.
+  // y: the depth dimension, with positive forward from the camera's
+  //    perspective.
+  // z: the vertical dimension, with positive upwards.
+  //
+  // Usually, the center of the microphone array will be treated as the origin
+  // (often the position of the camera).
+  //
+  // An empty vector indicates unknown positions.
+  std::vector<Point> mic_positions_;

[mcasas, 2015/09/02 03:05:37]

const?

[ajm, 2015/09/02 06:41:48]

The members aren't const to allow copy assignment and Reset(). That's hinted at
on l.119.

+
   int effects_;                   // Bitmask using PlatformEffectsMask.

[mcasas, 2015/09/02 03:05:37]

const?
And perhaps l.121-l.127 as well? 
Is strange that |mic_positions_| and |effects_| are not cleared
by Reset().

[mcasas, 2015/09/02 03:05:37]

const?
And perhaps l.121-l.127 as well? 
Is strange that |mic_positions_| and |effects_| are not cleared
by Reset().

[ajm, 2015/09/02 06:41:48]

As above.
I didn't change it because Reset() has no need to alter effects_ and
mic_positions_ in all uses. I agree resetting all members would be less
surprising though. Done.

 };