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..f921fd0b2c97a50943b9aa5d78e2d80eeaec36df 100644
--- a/media/audio/audio_parameters.h
+++ b/media/audio/audio_parameters.h
@@ -44,6 +44,16 @@ class MEDIA_EXPORT AudioParameters {
     kAudioCDSampleRate = 44100,
   };
 
+  // Used to carry whether certin platform (typically hardware) audio effects
+  // should be enabled.
+  struct PlatformEffects {
+    PlatformEffects() : echo_canceller(false) {}
+    bool operator==(const PlatformEffects& other) const {

[tommi (sloooow) - chröme, 2013/12/11 12:14:36]

document why you need the comparison operator. Usually we don't override
operators unless there's a specific need to (it goes against the style guide).
If you don't need it, you can still have an IsEqual method.

[ajm, 2013/12/11 17:46:49]

It was only to support the AudioParameters comparison operator, but I could just
as well call an IsEqual there.

+      return echo_canceller == other.echo_canceller;
+    }
+    bool echo_canceller;
+  };
+
   AudioParameters();
   AudioParameters(Format format, ChannelLayout channel_layout,
                   int sample_rate, int bits_per_sample,
@@ -81,9 +91,11 @@ 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_; }
+  const PlatformEffects& effects() const { return effects_; }
 
   // Set to CHANNEL_LAYOUT_DISCRETE with given number of channels.
   void SetDiscreteChannels(int channels);
+  void SetPlatformEffects(const PlatformEffects& effects);
 
   // Comparison with other AudioParams.
   bool operator==(const AudioParameters& other) const {
@@ -93,7 +105,8 @@ 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 +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.
+  PlatformEffects effects_;       // See PlatformEffects.
 };
 
 // Comparison is useful when AudioParameters is used with std structures.