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diff --git a/chromium/net/third_party/quiche/src/quic/core/congestion_control/rtt_stats.h b/chromium/net/third_party/quiche/src/quic/core/congestion_control/rtt_stats.h
new file mode 100644
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+++ b/chromium/net/third_party/quiche/src/quic/core/congestion_control/rtt_stats.h
@@ -0,0 +1,109 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// A convenience class to store rtt samples and calculate smoothed rtt.
+
+#ifndef QUICHE_QUIC_CORE_CONGESTION_CONTROL_RTT_STATS_H_
+#define QUICHE_QUIC_CORE_CONGESTION_CONTROL_RTT_STATS_H_
+
+#include <algorithm>
+#include <cstdint>
+
+#include "net/third_party/quiche/src/quic/core/quic_packets.h"
+#include "net/third_party/quiche/src/quic/core/quic_time.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_bug_tracker.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
+
+namespace quic {
+
+namespace test {
+class RttStatsPeer;
+}  // namespace test
+
+class QUIC_EXPORT_PRIVATE RttStats {
+ public:
+  RttStats();
+  RttStats(const RttStats&) = delete;
+  RttStats& operator=(const RttStats&) = delete;
+
+  // Updates the RTT from an incoming ack which is received |send_delta| after
+  // the packet is sent and the peer reports the ack being delayed |ack_delay|.
+  void UpdateRtt(QuicTime::Delta send_delta,
+                 QuicTime::Delta ack_delay,
+                 QuicTime now);
+
+  // Causes the smoothed_rtt to be increased to the latest_rtt if the latest_rtt
+  // is larger. The mean deviation is increased to the most recent deviation if
+  // it's larger.
+  void ExpireSmoothedMetrics();
+
+  // Called when connection migrates and rtt measurement needs to be reset.
+  void OnConnectionMigration();
+
+  // Returns the EWMA smoothed RTT for the connection.
+  // May return Zero if no valid updates have occurred.
+  QuicTime::Delta smoothed_rtt() const { return smoothed_rtt_; }
+
+  // Returns the EWMA smoothed RTT prior to the most recent RTT sample.
+  QuicTime::Delta previous_srtt() const { return previous_srtt_; }
+
+  QuicTime::Delta initial_rtt() const { return initial_rtt_; }
+
+  QuicTime::Delta SmoothedOrInitialRtt() const {
+    return smoothed_rtt_.IsZero() ? initial_rtt_ : smoothed_rtt_;
+  }
+
+  // Sets an initial RTT to be used for SmoothedRtt before any RTT updates.
+  void set_initial_rtt(QuicTime::Delta initial_rtt) {
+    if (initial_rtt.ToMicroseconds() <= 0) {
+      QUIC_BUG << "Attempt to set initial rtt to <= 0.";
+      return;
+    }
+    initial_rtt_ = initial_rtt;
+  }
+
+  // The most recent rtt measurement.
+  // May return Zero if no valid updates have occurred.
+  QuicTime::Delta latest_rtt() const { return latest_rtt_; }
+
+  // Returns the min_rtt for the entire connection.
+  // May return Zero if no valid updates have occurred.
+  QuicTime::Delta min_rtt() const { return min_rtt_; }
+
+  QuicTime::Delta mean_deviation() const { return mean_deviation_; }
+
+  QuicTime::Delta max_ack_delay() const { return max_ack_delay_; }
+
+  bool ignore_max_ack_delay() const { return ignore_max_ack_delay_; }
+
+  void set_ignore_max_ack_delay(bool ignore_max_ack_delay) {
+    ignore_max_ack_delay_ = ignore_max_ack_delay;
+  }
+
+  void set_initial_max_ack_delay(QuicTime::Delta initial_max_ack_delay) {
+    max_ack_delay_ = std::max(max_ack_delay_, initial_max_ack_delay);
+  }
+
+ private:
+  friend class test::RttStatsPeer;
+
+  QuicTime::Delta latest_rtt_;
+  QuicTime::Delta min_rtt_;
+  QuicTime::Delta smoothed_rtt_;
+  QuicTime::Delta previous_srtt_;
+  // Mean RTT deviation during this session.
+  // Approximation of standard deviation, the error is roughly 1.25 times
+  // larger than the standard deviation, for a normally distributed signal.
+  QuicTime::Delta mean_deviation_;
+  QuicTime::Delta initial_rtt_;
+  // The maximum ack delay observed over the connection after excluding ack
+  // delays that were too large to be included in an RTT measurement.
+  QuicTime::Delta max_ack_delay_;
+  // Whether to ignore the peer's max ack delay.
+  bool ignore_max_ack_delay_;
+};
+
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_CORE_CONGESTION_CONTROL_RTT_STATS_H_