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/agc2/rnn_vad/rnn_gru.h

@@ -0,0 +1,70 @@
+/*
+ *  Copyright (c) 2020 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_RNN_VAD_RNN_GRU_H_
+#define MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_RNN_GRU_H_
+
+#include <array>
+#include <vector>
+
+#include "absl/strings/string_view.h"
+#include "api/array_view.h"
+#include "modules/audio_processing/agc2/cpu_features.h"
+#include "modules/audio_processing/agc2/rnn_vad/vector_math.h"
+
+namespace webrtc {
+namespace rnn_vad {
+
+// Maximum number of units for a GRU layer.
+constexpr int kGruLayerMaxUnits = 24;
+
+// Recurrent layer with gated recurrent units (GRUs) with sigmoid and ReLU as
+// activation functions for the update/reset and output gates respectively.
+class GatedRecurrentLayer {
+ public:
+  // Ctor. `output_size` cannot be greater than `kGruLayerMaxUnits`.
+  GatedRecurrentLayer(int input_size,
+                      int output_size,
+                      rtc::ArrayView<const int8_t> bias,
+                      rtc::ArrayView<const int8_t> weights,
+                      rtc::ArrayView<const int8_t> recurrent_weights,
+                      const AvailableCpuFeatures& cpu_features,
+                      absl::string_view layer_name);
+  GatedRecurrentLayer(const GatedRecurrentLayer&) = delete;
+  GatedRecurrentLayer& operator=(const GatedRecurrentLayer&) = delete;
+  ~GatedRecurrentLayer();
+
+  // Returns the size of the input vector.
+  int input_size() const { return input_size_; }
+  // Returns the pointer to the first element of the output buffer.
+  const float* data() const { return state_.data(); }
+  // Returns the size of the output buffer.
+  int size() const { return output_size_; }
+
+  // Resets the GRU state.
+  void Reset();
+  // Computes the recurrent layer output and updates the status.
+  void ComputeOutput(rtc::ArrayView<const float> input);
+
+ private:
+  const int input_size_;
+  const int output_size_;
+  const std::vector<float> bias_;
+  const std::vector<float> weights_;
+  const std::vector<float> recurrent_weights_;
+  const VectorMath vector_math_;
+  // Over-allocated array with size equal to `output_size_`.
+  std::array<float, kGruLayerMaxUnits> state_;
+};
+
+}  // namespace rnn_vad
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_AGC2_RNN_VAD_RNN_GRU_H_