Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

webrtc/modules/audio_processing/voice_detection.h

@@ -0,0 +1,59 @@
+/*
+ *  Copyright (c) 2019 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef MODULES_AUDIO_PROCESSING_VOICE_DETECTION_H_
+#define MODULES_AUDIO_PROCESSING_VOICE_DETECTION_H_
+
+#include <stddef.h>
+
+#include <memory>
+
+#include "modules/audio_processing/include/audio_processing.h"
+
+namespace webrtc {
+
+class AudioBuffer;
+
+// The voice activity detection (VAD) component analyzes the stream to
+// determine if voice is present.
+class VoiceDetection {
+ public:
+  // Specifies the likelihood that a frame will be declared to contain voice.
+  // A higher value makes it more likely that speech will not be clipped, at
+  // the expense of more noise being detected as voice.
+  enum Likelihood {
+    kVeryLowLikelihood,
+    kLowLikelihood,
+    kModerateLikelihood,
+    kHighLikelihood
+  };
+
+  VoiceDetection(int sample_rate_hz, Likelihood likelihood);
+  ~VoiceDetection();
+
+  VoiceDetection(VoiceDetection&) = delete;
+  VoiceDetection& operator=(VoiceDetection&) = delete;
+
+  // Returns true if voice is detected in the current frame.
+  bool ProcessCaptureAudio(AudioBuffer* audio);
+
+  Likelihood likelihood() const { return likelihood_; }
+
+ private:
+  class Vad;
+
+  int sample_rate_hz_;
+  size_t frame_size_samples_;
+  Likelihood likelihood_;
+  std::unique_ptr<Vad> vad_;
+};
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_VOICE_DETECTION_H_