Bump to WebRTC M120 release

Some API deprecation -- ExperimentalAgc and ExperimentalNs are gone.
We're continuing to carry iSAC even though it's gone upstream, but maybe
we'll want to drop that soon.

webrtc/modules/audio_processing/ns/noise_suppressor.cc

@@ -13,6 +13,7 @@
 #include <math.h>
 #include <stdlib.h>
 #include <string.h>
+
 #include <algorithm>
 
 #include "modules/audio_processing/ns/fast_math.h"
@@ -448,6 +449,12 @@ void NoiseSuppressor::Process(AudioBuffer* audio) {
     }
   }
 
+  // Only do the below processing if the output of the audio processing module
+  // is used.
+  if (!capture_output_used_) {
+    return;
+  }
+
   // Aggregate the Wiener filters for all channels.
   std::array<float, kFftSizeBy2Plus1> filter_data;
   rtc::ArrayView<const float, kFftSizeBy2Plus1> filter = filter_data;