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..8c6458c417d3d25fdd58d49b88fb684638284ad7 100644
--- a/media/audio/audio_parameters.h
+++ b/media/audio/audio_parameters.h
@@ -56,6 +56,10 @@ class MEDIA_EXPORT AudioParameters {
              int channels, int input_channels,
              int sample_rate, int bits_per_sample,
              int frames_per_buffer);
+  void Reset(Format format, ChannelLayout channel_layout,
+             int channels, int input_channels,
+             int sample_rate, int bits_per_sample,
+             int frames_per_buffer, bool use_platform_aec);

[ajm, 2013/12/06 04:30:49]

If we agree on this approach, I'll add use_platform_aec to the existing Reset().
I just didn't want to change the many call sites needlessly.

 
   // Checks that all values are in the expected range. All limits are specified
   // in media::Limits.
@@ -81,9 +85,15 @@ 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_; }
+  bool use_platform_aec() const {
+    return use_platform_aec_;
+  }
 
   // Set to CHANNEL_LAYOUT_DISCRETE with given number of channels.
   void SetDiscreteChannels(int channels);
+  void set_use_platform_aec(bool use) {
+    use_platform_aec_ = use;
+  }
 
   // Comparison with other AudioParams.
   bool operator==(const AudioParameters& other) const {
@@ -93,7 +103,8 @@ 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() &&
+           use_platform_aec_ == other.use_platform_aec();
   }
 
  private:
@@ -108,6 +119,8 @@ class MEDIA_EXPORT AudioParameters {
   int input_channels_;            // Optional number of input channels.
                                   // Normally 0, but can be set to specify
                                   // synchronized I/O.
+  bool use_platform_aec_;         // Platform AEC is available, or should be
+                                  // enabled, depending on context.
 };
 
 // Comparison is useful when AudioParameters is used with std structures.
@@ -122,7 +135,9 @@ inline bool operator<(const AudioParameters& a, const AudioParameters& b) {
     return a.sample_rate() < b.sample_rate();
   if (a.bits_per_sample() != b.bits_per_sample())
     return a.bits_per_sample() < b.bits_per_sample();
-  return a.frames_per_buffer() < b.frames_per_buffer();
+  if (a.frames_per_buffer() != b.frames_per_buffer())
+    return a.frames_per_buffer() < b.frames_per_buffer();
+  return a.use_platform_aec() < b.use_platform_aec();
 }
 
 }  // namespace media