Change kEnableAudioTrackProcessing to a disable flag and remove finch code

content/renderer/media/media_stream_audio_processor.h

Index: content/renderer/media/media_stream_audio_processor.h
diff --git a/content/renderer/media/media_stream_audio_processor.h b/content/renderer/media/media_stream_audio_processor.h
index 56208782b0c637142ed936a31dab19a108e31b3f..b97cb395e464191eeab8e22dedf7c9654a11507f 100644
--- a/content/renderer/media/media_stream_audio_processor.h
+++ b/content/renderer/media/media_stream_audio_processor.h
@@ -46,8 +46,8 @@ class CONTENT_EXPORT MediaStreamAudioProcessor :
     NON_EXPORTED_BASE(public WebRtcPlayoutDataSource::Sink),
     NON_EXPORTED_BASE(public AudioProcessorInterface) {
  public:
-  // Returns true if |kEnableAudioTrackProcessing| is on or if the
-  // |MediaStreamAudioTrackProcessing| finch experiment is enabled.
+  // Returns false if |kDisableAudioTrackProcessing| is set to true, otherwise
+  // returns true.
   static bool IsAudioTrackProcessingEnabled();
 
   // |playout_data_source| is used to register this class as a sink to the