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/agc2/noise_spectrum_estimator.h

@@ -0,0 +1,42 @@
+/*
+ *  Copyright (c) 2016 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_AGC2_NOISE_SPECTRUM_ESTIMATOR_H_
+#define MODULES_AUDIO_PROCESSING_AGC2_NOISE_SPECTRUM_ESTIMATOR_H_
+
+#include "api/array_view.h"
+
+namespace webrtc {
+
+class ApmDataDumper;
+
+class NoiseSpectrumEstimator {
+ public:
+  explicit NoiseSpectrumEstimator(ApmDataDumper* data_dumper);
+
+  NoiseSpectrumEstimator() = delete;
+  NoiseSpectrumEstimator(const NoiseSpectrumEstimator&) = delete;
+  NoiseSpectrumEstimator& operator=(const NoiseSpectrumEstimator&) = delete;
+
+  void Initialize();
+  void Update(rtc::ArrayView<const float> spectrum, bool first_update);
+
+  rtc::ArrayView<const float> GetNoiseSpectrum() const {
+    return rtc::ArrayView<const float>(noise_spectrum_);
+  }
+
+ private:
+  ApmDataDumper* data_dumper_;
+  float noise_spectrum_[65];
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_AGC2_NOISE_SPECTRUM_ESTIMATOR_H_