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..089581c0b05c1bd7604412ffe05765505cb150fb 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,

[ajm, 2013/12/12 01:51:28]

This existing constructor didn't have many call sites, so I opted to add a
parameter to it rather than creating a new one.

(Also, with the addition of an int to the new constructor, the prototypes were
ambiguous)

                   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,
@@ -81,6 +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_; }
+  int effects() const { return effects_; }
 
   // Set to CHANNEL_LAYOUT_DISCRETE with given number of channels.
   void SetDiscreteChannels(int channels);
@@ -93,7 +106,8 @@ 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:
@@ -108,6 +122,7 @@ 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 of PlatformEffects.
 };
 
 // Comparison is useful when AudioParameters is used with std structures.