Enable platform echo cancellation through the AudioRecord path.

media/audio/mac/audio_manager_mac.cc

Index: media/audio/mac/audio_manager_mac.cc
diff --git a/media/audio/mac/audio_manager_mac.cc b/media/audio/mac/audio_manager_mac.cc
index 2aa0ef53cc277a430c69ab9b8eedc5b138779496..be7dddd5bb68c23c830f0fd3592cd75ce274ae32 100644
--- a/media/audio/mac/audio_manager_mac.cc
+++ b/media/audio/mac/audio_manager_mac.cc
@@ -674,16 +674,20 @@ AudioParameters AudioManagerMac::GetPreferredOutputStreamParameters(
     }
   }
 
+  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);
-
-  if (channel_layout == CHANNEL_LAYOUT_UNSUPPORTED)
-    params.SetDiscreteChannels(hardware_channels);
+      buffer_size,
+      AudioParameters::NO_EFFECTS);
 
   return params;
 }