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diff --git a/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.h b/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.h
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+++ b/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.h
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+/*
+ *  Copyright (c) 2017 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 RTC_BASE_NUMERICS_HISTOGRAM_PERCENTILE_COUNTER_H_
+#define RTC_BASE_NUMERICS_HISTOGRAM_PERCENTILE_COUNTER_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <map>
+#include <vector>
+
+#include "absl/types/optional.h"
+
+namespace rtc {
+// Calculates percentiles on the stream of data. Use `Add` methods to add new
+// values. Use `GetPercentile` to get percentile of the currently added values.
+class HistogramPercentileCounter {
+ public:
+  // Values below `long_tail_boundary` are stored as the histogram in an array.
+  // Values above - in a map.
+  explicit HistogramPercentileCounter(uint32_t long_tail_boundary);
+  ~HistogramPercentileCounter();
+  void Add(uint32_t value);
+  void Add(uint32_t value, size_t count);
+  void Add(const HistogramPercentileCounter& other);
+  // Argument should be from 0 to 1.
+  absl::optional<uint32_t> GetPercentile(float fraction);
+
+ private:
+  std::vector<size_t> histogram_low_;
+  std::map<uint32_t, size_t> histogram_high_;
+  const uint32_t long_tail_boundary_;
+  size_t total_elements_;
+  size_t total_elements_low_;
+};
+}  // namespace rtc
+#endif  // RTC_BASE_NUMERICS_HISTOGRAM_PERCENTILE_COUNTER_H_