Enable platform echo cancellation through the AudioRecord path.

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 9b86d31186a7c2d33f6f0388b36a344f0855cd97..62ff4fd48f1eb1a3098b46491e254af67c0dbf89 100644
--- a/media/audio/audio_parameters.h
+++ b/media/audio/audio_parameters.h
@@ -44,6 +44,13 @@ class MEDIA_EXPORT AudioParameters {
     kAudioCDSampleRate = 44100,
   };
 
+  // Bitmasks to determine whether certain platform (typically hardware) audio
+  // effects should be enabled.
+  enum PlatformEffectsMask {
+    NO_EFFECTS = 0x0,
+    ECHO_CANCELLER = 0x1
+  };
+
   AudioParameters();
   AudioParameters(Format format, ChannelLayout channel_layout,
                   int sample_rate, int bits_per_sample,
@@ -51,7 +58,12 @@ class MEDIA_EXPORT AudioParameters {
   AudioParameters(Format format, ChannelLayout channel_layout,
                   int input_channels,
                   int sample_rate, int bits_per_sample,
-                  int frames_per_buffer);
+                  int frames_per_buffer, int effects);
+  AudioParameters(Format format, ChannelLayout channel_layout,
+                  int channels, int input_channels,
+                  int sample_rate, int bits_per_sample,
+                  int frames_per_buffer, int effects);
+
   void Reset(Format format, ChannelLayout channel_layout,
              int channels, int input_channels,
              int sample_rate, int bits_per_sample,
@@ -81,9 +93,7 @@ class MEDIA_EXPORT AudioParameters {
   int frames_per_buffer() const { return frames_per_buffer_; }
   int channels() const { return channels_; }
   int input_channels() const { return input_channels_; }
-
-  // Set to CHANNEL_LAYOUT_DISCRETE with given number of channels.
-  void SetDiscreteChannels(int channels);
+  int effects() const { return effects_; }
 
   // Comparison with other AudioParams.
   bool operator==(const AudioParameters& other) const {
@@ -93,10 +103,13 @@ class MEDIA_EXPORT AudioParameters {
            channels_ == other.channels() &&
            input_channels_ == other.input_channels() &&
            bits_per_sample_ == other.bits_per_sample() &&
-           frames_per_buffer_ == other.frames_per_buffer();
+           frames_per_buffer_ == other.frames_per_buffer() &&
+           effects_ == other.effects();
   }
 
  private:
+  // These members are mutable to support entire struct assignment. They should
+  // not be mutated individually.

[ajm, 2013/12/12 03:36:03]

Dale, Tommi: To legitimize this comment, I removed the SetDiscreteChannels()
method, which was only used in a single unittest file. Is that OK?

[tommi (sloooow) - chröme, 2013/12/12 12:05:31]

sgtm.

Dale - afaict we never actually set layout to CHANNEL_LAYOUT_DISCRETE.  Should
we remove that enum value?

[ajm, 2013/12/12 17:35:05]

It was actually used in audio_manager_mac.cc as well; codesearch cross-reference
didn't catch that oddly (perhaps it only evaluates the calls on Linux?). Updated
now.

   Format format_;                 // Format of the stream.
   ChannelLayout channel_layout_;  // Order of surround sound channels.
   int sample_rate_;               // Sampling frequency/rate.
@@ -108,6 +121,7 @@ class MEDIA_EXPORT AudioParameters {
   int input_channels_;            // Optional number of input channels.
                                   // Normally 0, but can be set to specify
                                   // synchronized I/O.
+  int effects_;                   // Bitmask using PlatformEffectsMask.
 };
 
 // Comparison is useful when AudioParameters is used with std structures.