Revert 240548 "Enable platform echo cancellation through the Aud..."

trunk/src/media/audio/mac/audio_manager_mac.cc

Index: trunk/src/media/audio/mac/audio_manager_mac.cc
===================================================================
--- trunk/src/media/audio/mac/audio_manager_mac.cc	(revision 240589)
+++ trunk/src/media/audio/mac/audio_manager_mac.cc	(working copy)
@@ -674,21 +674,17 @@
     }
   }
 
-  if (channel_layout == CHANNEL_LAYOUT_UNSUPPORTED)
-    channel_layout = CHANNEL_LAYOUT_DISCRETE;
-  else
-    hardware_channels = ChannelLayoutToChannelCount(channel_layout);
-
   AudioParameters params(
       AudioParameters::AUDIO_PCM_LOW_LATENCY,
       channel_layout,
-      hardware_channels,
       input_channels,
       hardware_sample_rate,
       16,
-      buffer_size,
-      AudioParameters::NO_EFFECTS);
+      buffer_size);
 
+  if (channel_layout == CHANNEL_LAYOUT_UNSUPPORTED)
+    params.SetDiscreteChannels(hardware_channels);
+
   return params;
 }