Plumb |input_channels| all the way to AudioManager

content/renderer/media/webrtc_audio_renderer.cc

Index: content/renderer/media/webrtc_audio_renderer.cc
===================================================================
--- content/renderer/media/webrtc_audio_renderer.cc	(revision 181072)
+++ content/renderer/media/webrtc_audio_renderer.cc	(working copy)
@@ -157,7 +157,7 @@
   }
 
   source_params.Reset(media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
-                      channel_layout, sample_rate, 16, buffer_size);
+                      channel_layout, 0, sample_rate, 16, buffer_size);
 
   // Set up audio parameters for the sink, i.e., the native audio output stream.
   // We strive to open up using native parameters to achieve best possible
@@ -169,7 +169,7 @@
 
   buffer_size = hardware_config->GetOutputBufferSize();
   sink_params.Reset(media::AudioParameters::AUDIO_PCM_LOW_LATENCY,
-                    channel_layout, sample_rate, 16, buffer_size);
+                    channel_layout, 0, sample_rate, 16, buffer_size);
 
   // Create a FIFO if re-buffering is required to match the source input with
   // the sink request. The source acts as provider here and the sink as