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

media/audio/audio_util.cc

Index: media/audio/audio_util.cc
diff --git a/media/audio/audio_util.cc b/media/audio/audio_util.cc
index 8989eb9c91cede98062fda2837639c39051b959c..781d2b771aa7e3b4a037e251e1ded9a62fdeb88e 100644
--- a/media/audio/audio_util.cc
+++ b/media/audio/audio_util.cc
@@ -337,6 +337,22 @@ size_t GetAudioHardwareBufferSize() {
 #endif
 }
 
+size_t GetAudioInputHardwareChannelCount() {
+  enum channel_layout { MONO = 1, STEREO = 2 };
+#if defined(OS_MACOSX)
+  return MONO;
+#elif defined(OS_WIN)
+  if (!IsWASAPISupported()) {
+    // Fall back to Windows Wave implementation on Windows XP or lower and
+    // use stereo by default.
+    return STEREO;
+  }
+  return WASAPIAudioInputStream::HardwareChannelCount(eConsole);
+#else
+  return STEREO;
+#endif
+}
+
 // When transferring data in the shared memory, first word is size of data
 // in bytes. Actual data starts immediately after it.