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diff --git a/third_party/libwebrtc/common_video/frame_rate_estimator.h b/third_party/libwebrtc/common_video/frame_rate_estimator.h
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+/*
+ *  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 COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_
+#define COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_
+
+#include <deque>
+
+#include "absl/types/optional.h"
+#include "api/units/time_delta.h"
+#include "api/units/timestamp.h"
+
+namespace webrtc {
+
+// Class used to estimate a frame-rate using inter-frame intervals.
+// Some notes on usage:
+// This class is intended to accurately estimate the frame rate during a
+// continuous stream. Unlike a traditional rate estimator that looks at number
+// of data points within a time window, if the input stops this implementation
+// will not smoothly fall down towards 0. This is done so that the estimated
+// fps is not affected by edge conditions like if we sample just before or just
+// after the next frame.
+// To avoid problems if a stream is stopped and restarted (where estimated fps
+// could look too low), users of this class should explicitly call Reset() on
+// restart.
+// Also note that this class is not thread safe, it's up to the user to guard
+// against concurrent access.
+class FrameRateEstimator {
+ public:
+  explicit FrameRateEstimator(TimeDelta averaging_window);
+
+  // Insert a frame, potentially culling old frames that falls outside the
+  // averaging window.
+  void OnFrame(Timestamp time);
+
+  // Get the current average FPS, based on the frames currently in the window.
+  absl::optional<double> GetAverageFps() const;
+
+  // Move the window so it ends at `now`, and return the new fps estimate.
+  absl::optional<double> GetAverageFps(Timestamp now);
+
+  // Completely clear the averaging window.
+  void Reset();
+
+ private:
+  void CullOld(Timestamp now);
+  const TimeDelta averaging_window_;
+  std::deque<Timestamp> frame_times_;
+};
+
+}  // namespace webrtc
+
+#endif  // COMMON_VIDEO_FRAME_RATE_ESTIMATOR_H_