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/ns/ns_fft.h

@@ -0,0 +1,45 @@
+/*
+ *  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_NS_NS_FFT_H_
+#define MODULES_AUDIO_PROCESSING_NS_NS_FFT_H_
+
+#include <vector>
+
+#include "api/array_view.h"
+#include "modules/audio_processing/ns/ns_common.h"
+
+namespace webrtc {
+
+// Wrapper class providing 256 point FFT functionality.
+class NrFft {
+ public:
+  NrFft();
+  NrFft(const NrFft&) = delete;
+  NrFft& operator=(const NrFft&) = delete;
+
+  // Transforms the signal from time to frequency domain.
+  void Fft(rtc::ArrayView<float, kFftSize> time_data,
+           rtc::ArrayView<float, kFftSize> real,
+           rtc::ArrayView<float, kFftSize> imag);
+
+  // Transforms the signal from frequency to time domain.
+  void Ifft(rtc::ArrayView<const float> real,
+            rtc::ArrayView<const float> imag,
+            rtc::ArrayView<float> time_data);
+
+ private:
+  std::vector<size_t> bit_reversal_state_;
+  std::vector<float> tables_;
+};
+
+}  // namespace webrtc
+
+#endif  // MODULES_AUDIO_PROCESSING_NS_NS_FFT_H_