Use the AudioProcessing float interface in MediaStreamAudioProcessor.

media/base/audio_bus.h

Index: media/base/audio_bus.h
diff --git a/media/base/audio_bus.h b/media/base/audio_bus.h
index c78486e5e00aa5f00ce567275f0025681778ec21..d24794497f00fb832eb363700c14899896e8586b 100644
--- a/media/base/audio_bus.h
+++ b/media/base/audio_bus.h
@@ -92,6 +92,10 @@ class MEDIA_EXPORT AudioBus {
   const float* channel(int channel) const { return channel_data_[channel]; }
   void SetChannelData(int channel, float* data);
 
+  // Returns an array of pointers to each channel.
+  float** channel_data() { return &channel_data_[0]; }

[tommi (sloooow) - chröme, 2014/08/06 13:45:56]

I would like to get Dale to look at this (and perhaps some of the other changes
if he can).

I'm currently sheriffing so I have time occasionally but not continuously :) 
I'll take another round probably later today.

+  const float* const* channel_data() const { return &channel_data_[0]; }
+
   int channels() const { return static_cast<int>(channel_data_.size()); }
   int frames() const { return frames_; }
   void set_frames(int frames);