Adds support for 16kHz input sample rate and mono channel config. in WebRTC.

media/audio/audio_util.h

Index: media/audio/audio_util.h
diff --git a/media/audio/audio_util.h b/media/audio/audio_util.h
index 278779ae308b30438b5893baea7d182010126c36..d5a0428db349d8807dbc68e13a036a958224b926 100644
--- a/media/audio/audio_util.h
+++ b/media/audio/audio_util.h
@@ -90,6 +90,9 @@ MEDIA_EXPORT double GetAudioInputHardwareSampleRate();
 // at without glitches.  The buffer size is in sample-frames.
 MEDIA_EXPORT size_t GetAudioHardwareBufferSize();
 
+// Returns the default number of channels for the audio input hardware.
+MEDIA_EXPORT size_t GetAudioInputHardwareChannelCount();
+
 // Functions that handle data buffer passed between processes in the shared
 // memory. Called on both IPC sides.