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/agc2_testing_common.cc

@@ -0,0 +1,33 @@
+/*
+ *  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/agc2/agc2_testing_common.h"
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+
+namespace test {
+
+std::vector<double> LinSpace(const double l,
+                             const double r,
+                             size_t num_points) {
+  RTC_CHECK(num_points >= 2);
+  std::vector<double> points(num_points);
+  const double step = (r - l) / (num_points - 1.0);
+  points[0] = l;
+  for (size_t i = 1; i < num_points - 1; i++) {
+    points[i] = static_cast<double>(l) + i * step;
+  }
+  points[num_points - 1] = r;
+  return points;
+}
+}  // namespace test
+}  // namespace webrtc