Plumb |input_channels| all the way to AudioManager

media/audio/mac/audio_manager_mac.cc

Index: media/audio/mac/audio_manager_mac.cc
===================================================================
--- media/audio/mac/audio_manager_mac.cc	(revision 181072)
+++ media/audio/mac/audio_manager_mac.cc	(working copy)
@@ -283,10 +283,12 @@
     const AudioParameters& params) {
   DCHECK_EQ(AudioParameters::AUDIO_PCM_LOW_LATENCY, params.format());
 
-  // TODO(crogers): remove once we properly handle input device selection.
+  // TODO(crogers): support more than stereo input.
+  // TODO(crogers): remove flag once we handle input device selection.
   // https://code.google.com/p/chromium/issues/detail?id=147327
-  if (CommandLine::ForCurrentProcess()->HasSwitch(
-      switches::kEnableWebAudioInput)) {
+  if (params.input_channels() == 2 &&
+      CommandLine::ForCurrentProcess()->HasSwitch(
+          switches::kEnableWebAudioInput)) {
     if (HasUnifiedDefaultIO())
       return new AudioHardwareUnifiedStream(this, params);
 
@@ -328,7 +330,8 @@
     // Specifically, this is a limitation of AudioSynchronizedStream which
     // can be removed as part of the work to consolidate these back-ends.
     return AudioParameters(
-        AudioParameters::AUDIO_PCM_LOW_LATENCY, CHANNEL_LAYOUT_STEREO,
+        AudioParameters::AUDIO_PCM_LOW_LATENCY,
+        CHANNEL_LAYOUT_STEREO, input_params.input_channels(),
         GetAudioHardwareSampleRate(), 16, GetAudioHardwareBufferSize());
   }