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/aec3/reverb_model.cc

@@ -0,0 +1,59 @@
+/*
+ *  Copyright (c) 2018 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.
+ */
+
+#include "modules/audio_processing/aec3/reverb_model.h"
+
+#include <stddef.h>
+
+#include <algorithm>
+#include <functional>
+
+#include "api/array_view.h"
+
+namespace webrtc {
+
+ReverbModel::ReverbModel() {
+  Reset();
+}
+
+ReverbModel::~ReverbModel() = default;
+
+void ReverbModel::Reset() {
+  reverb_.fill(0.);
+}
+
+void ReverbModel::UpdateReverbNoFreqShaping(
+    rtc::ArrayView<const float> power_spectrum,
+    float power_spectrum_scaling,
+    float reverb_decay) {
+  if (reverb_decay > 0) {
+    // Update the estimate of the reverberant power.
+    for (size_t k = 0; k < power_spectrum.size(); ++k) {
+      reverb_[k] = (reverb_[k] + power_spectrum[k] * power_spectrum_scaling) *
+                   reverb_decay;
+    }
+  }
+}
+
+void ReverbModel::UpdateReverb(
+    rtc::ArrayView<const float> power_spectrum,
+    rtc::ArrayView<const float> power_spectrum_scaling,
+    float reverb_decay) {
+  if (reverb_decay > 0) {
+    // Update the estimate of the reverberant power.
+    for (size_t k = 0; k < power_spectrum.size(); ++k) {
+      reverb_[k] =
+          (reverb_[k] + power_spectrum[k] * power_spectrum_scaling[k]) *
+          reverb_decay;
+    }
+  }
+}
+
+}  // namespace webrtc