trivial change to remove the hard coding to mono as the output channel layout in MSAP.

content/renderer/media/media_stream_audio_processor.cc

Index: content/renderer/media/media_stream_audio_processor.cc
diff --git a/content/renderer/media/media_stream_audio_processor.cc b/content/renderer/media/media_stream_audio_processor.cc
index 4c1a2c90ab299c27846cebd1c56e730cc9f0f22a..11e889259c0045346b9e5714ade5649ef5aa6fdf 100644
--- a/content/renderer/media/media_stream_audio_processor.cc
+++ b/content/renderer/media/media_stream_audio_processor.cc
@@ -376,7 +376,8 @@ void MediaStreamAudioProcessor::InitializeCaptureConverter(
   const int sink_sample_rate = audio_processing_ ?
       kAudioProcessingSampleRate : source_params.sample_rate();
   const media::ChannelLayout sink_channel_layout = audio_processing_ ?
-      media::CHANNEL_LAYOUT_MONO : source_params.channel_layout();
+      media::GuessChannelLayout(kAudioProcessingNumberOfChannel) :
+      source_params.channel_layout();
 
   // WebRtc AudioProcessing requires 10ms as its packet size. We use this
   // native size when processing is enabled. While processing is disabled, and