Adding upstream version 115.7.0esr.upstream/115.7.0esrupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

42 files changed, 5122 insertions, 0 deletions

diff --git a/third_party/libwebrtc/rtc_base/numerics/divide_round.h b/third_party/libwebrtc/rtc_base/numerics/divide_round.h
new file mode 100644
index 0000000000..90c67fca3c
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/divide_round.h
@@ -0,0 +1,60 @@
+/*
+ *  Copyright 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 RTC_BASE_NUMERICS_DIVIDE_ROUND_H_
+#define RTC_BASE_NUMERICS_DIVIDE_ROUND_H_
+
+#include <type_traits>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/safe_compare.h"
+
+namespace webrtc {
+
+template <typename Dividend, typename Divisor>
+inline auto constexpr DivideRoundUp(Dividend dividend, Divisor divisor) {
+  static_assert(std::is_integral<Dividend>(), "");
+  static_assert(std::is_integral<Divisor>(), "");
+  RTC_DCHECK_GE(dividend, 0);
+  RTC_DCHECK_GT(divisor, 0);
+
+  auto quotient = dividend / divisor;
+  auto remainder = dividend % divisor;
+  return quotient + (remainder > 0 ? 1 : 0);
+}
+
+template <typename Dividend, typename Divisor>
+inline auto constexpr DivideRoundToNearest(Dividend dividend, Divisor divisor) {
+  static_assert(std::is_integral<Dividend>(), "");
+  static_assert(std::is_integral<Divisor>(), "");
+  RTC_DCHECK_GT(divisor, 0);
+
+  if (dividend < Dividend{0}) {
+    auto half_of_divisor = divisor / 2;
+    auto quotient = dividend / divisor;
+    auto remainder = dividend % divisor;
+    if (rtc::SafeGt(-remainder, half_of_divisor)) {
+      --quotient;
+    }
+    return quotient;
+  }
+
+  auto half_of_divisor = (divisor - 1) / 2;
+  auto quotient = dividend / divisor;
+  auto remainder = dividend % divisor;
+  if (rtc::SafeGt(remainder, half_of_divisor)) {
+    ++quotient;
+  }
+  return quotient;
+}
+
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_DIVIDE_ROUND_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/divide_round_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/divide_round_unittest.cc
new file mode 100644
index 0000000000..00548e1cb2
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/divide_round_unittest.cc
@@ -0,0 +1,178 @@
+/*
+ *  Copyright 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.
+ */
+
+#include "rtc_base/numerics/divide_round.h"
+
+#include <limits>
+
+#include "test/gtest.h"
+
+namespace webrtc {
+namespace {
+
+TEST(DivideRoundUpTest, CanBeUsedAsConstexpr) {
+  static_assert(DivideRoundUp(5, 1) == 5, "");
+  static_assert(DivideRoundUp(5, 2) == 3, "");
+}
+
+TEST(DivideRoundUpTest, ReturnsZeroForZeroDividend) {
+  EXPECT_EQ(DivideRoundUp(uint8_t{0}, 1), 0);
+  EXPECT_EQ(DivideRoundUp(uint8_t{0}, 3), 0);
+  EXPECT_EQ(DivideRoundUp(int{0}, 1), 0);
+  EXPECT_EQ(DivideRoundUp(int{0}, 3), 0);
+}
+
+TEST(DivideRoundUpTest, WorksForMaxDividend) {
+  EXPECT_EQ(DivideRoundUp(uint8_t{255}, 2), 128);
+  EXPECT_EQ(DivideRoundUp(std::numeric_limits<int>::max(), 2),
+            std::numeric_limits<int>::max() / 2 +
+                (std::numeric_limits<int>::max() % 2));
+}
+
+TEST(DivideRoundToNearestTest, CanBeUsedAsConstexpr) {
+  static constexpr int kOne = DivideRoundToNearest(5, 4);
+  static constexpr int kTwo = DivideRoundToNearest(7, 4);
+  static_assert(kOne == 1);
+  static_assert(kTwo == 2);
+  static_assert(DivideRoundToNearest(-5, 4) == -1);
+  static_assert(DivideRoundToNearest(-7, 4) == -2);
+}
+
+TEST(DivideRoundToNearestTest, DivideByOddNumber) {
+  EXPECT_EQ(DivideRoundToNearest(-5, 3), -2);
+  EXPECT_EQ(DivideRoundToNearest(-4, 3), -1);
+  EXPECT_EQ(DivideRoundToNearest(-3, 3), -1);
+  EXPECT_EQ(DivideRoundToNearest(-2, 3), -1);
+  EXPECT_EQ(DivideRoundToNearest(-1, 3), 0);
+  EXPECT_EQ(DivideRoundToNearest(0, 3), 0);
+  EXPECT_EQ(DivideRoundToNearest(1, 3), 0);
+  EXPECT_EQ(DivideRoundToNearest(2, 3), 1);
+  EXPECT_EQ(DivideRoundToNearest(3, 3), 1);
+  EXPECT_EQ(DivideRoundToNearest(4, 3), 1);
+  EXPECT_EQ(DivideRoundToNearest(5, 3), 2);
+  EXPECT_EQ(DivideRoundToNearest(6, 3), 2);
+}
+
+TEST(DivideRoundToNearestTest, DivideByEvenNumberTieRoundsUp) {
+  EXPECT_EQ(DivideRoundToNearest(-7, 4), -2);
+  EXPECT_EQ(DivideRoundToNearest(-6, 4), -1);
+  EXPECT_EQ(DivideRoundToNearest(-5, 4), -1);
+  EXPECT_EQ(DivideRoundToNearest(-4, 4), -1);
+  EXPECT_EQ(DivideRoundToNearest(-3, 4), -1);
+  EXPECT_EQ(DivideRoundToNearest(-2, 4), 0);
+  EXPECT_EQ(DivideRoundToNearest(-1, 4), 0);
+  EXPECT_EQ(DivideRoundToNearest(0, 4), 0);
+  EXPECT_EQ(DivideRoundToNearest(1, 4), 0);
+  EXPECT_EQ(DivideRoundToNearest(2, 4), 1);
+  EXPECT_EQ(DivideRoundToNearest(3, 4), 1);
+  EXPECT_EQ(DivideRoundToNearest(4, 4), 1);
+  EXPECT_EQ(DivideRoundToNearest(5, 4), 1);
+  EXPECT_EQ(DivideRoundToNearest(6, 4), 2);
+  EXPECT_EQ(DivideRoundToNearest(7, 4), 2);
+}
+
+TEST(DivideRoundToNearestTest, LargeDivisor) {
+  EXPECT_EQ(DivideRoundToNearest(std::numeric_limits<int>::max() - 1,
+                                 std::numeric_limits<int>::max()),
+            1);
+  EXPECT_EQ(DivideRoundToNearest(std::numeric_limits<int>::min(),
+                                 std::numeric_limits<int>::max()),
+            -1);
+}
+
+TEST(DivideRoundToNearestTest, DivideSmallTypeByLargeType) {
+  uint8_t small = 0xff;
+  uint16_t large = 0xffff;
+  EXPECT_EQ(DivideRoundToNearest(small, large), 0);
+}
+
+using IntegerTypes = ::testing::Types<int8_t,
+                                      int16_t,
+                                      int32_t,
+                                      int64_t,
+                                      uint8_t,
+                                      uint16_t,
+                                      uint32_t,
+                                      uint64_t>;
+template <typename T>
+class DivideRoundTypedTest : public ::testing::Test {};
+TYPED_TEST_SUITE(DivideRoundTypedTest, IntegerTypes);
+
+TYPED_TEST(DivideRoundTypedTest, RoundToNearestPreservesType) {
+  static_assert(
+      std::is_same<decltype(DivideRoundToNearest(TypeParam{100}, int8_t{3})),
+                   decltype(TypeParam{100} / int8_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundToNearest(TypeParam{100}, int16_t{3})),
+                   decltype(TypeParam{100} / int16_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundToNearest(TypeParam{100}, int32_t{3})),
+                   decltype(TypeParam{100} / int32_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundToNearest(TypeParam{100}, int64_t{3})),
+                   decltype(TypeParam{100} / int64_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundToNearest(TypeParam{100}, uint8_t{3})),
+                   decltype(TypeParam{100} / uint8_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundToNearest(TypeParam{100}, uint16_t{3})),
+                   decltype(TypeParam{100} / uint16_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundToNearest(TypeParam{100}, uint32_t{3})),
+                   decltype(TypeParam{100} / uint32_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundToNearest(TypeParam{100}, uint64_t{3})),
+                   decltype(TypeParam{100} / uint64_t{3})>::value,
+      "");
+}
+
+TYPED_TEST(DivideRoundTypedTest, RoundUpPreservesType) {
+  static_assert(std::is_same<decltype(DivideRoundUp(TypeParam{100}, int8_t{3})),
+                             decltype(TypeParam{100} / int8_t{3})>::value,
+                "");
+  static_assert(
+      std::is_same<decltype(DivideRoundUp(TypeParam{100}, int16_t{3})),
+                   decltype(TypeParam{100} / int16_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundUp(TypeParam{100}, int32_t{3})),
+                   decltype(TypeParam{100} / int32_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundUp(TypeParam{100}, int64_t{3})),
+                   decltype(TypeParam{100} / int64_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundUp(TypeParam{100}, uint8_t{3})),
+                   decltype(TypeParam{100} / uint8_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundUp(TypeParam{100}, uint16_t{3})),
+                   decltype(TypeParam{100} / uint16_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundUp(TypeParam{100}, uint32_t{3})),
+                   decltype(TypeParam{100} / uint32_t{3})>::value,
+      "");
+  static_assert(
+      std::is_same<decltype(DivideRoundUp(TypeParam{100}, uint64_t{3})),
+                   decltype(TypeParam{100} / uint64_t{3})>::value,
+      "");
+}
+
+}  // namespace
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average.cc b/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average.cc
new file mode 100644
index 0000000000..b426fdeed7
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average.cc
@@ -0,0 +1,82 @@
+/*
+ *  Copyright 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.
+ */
+
+#include "rtc_base/numerics/event_based_exponential_moving_average.h"
+
+#include <cmath>
+
+#include "rtc_base/checks.h"
+
+namespace {
+
+// For a normal distributed value, the 95% double sided confidence interval is
+// is 1.96 * stddev.
+constexpr double ninetyfive_percent_confidence = 1.96;
+
+}  // namespace
+
+namespace rtc {
+
+// `half_time` specifies how much weight will be given to old samples,
+// a sample gets exponentially less weight so that it's 50%
+// after `half_time` time units has passed.
+EventBasedExponentialMovingAverage::EventBasedExponentialMovingAverage(
+    int half_time) {
+  SetHalfTime(half_time);
+}
+
+void EventBasedExponentialMovingAverage::SetHalfTime(int half_time) {
+  tau_ = static_cast<double>(half_time) / log(2);
+  Reset();
+}
+
+void EventBasedExponentialMovingAverage::Reset() {
+  value_ = std::nan("uninit");
+  sample_variance_ = std::numeric_limits<double>::infinity();
+  estimator_variance_ = 1;
+  last_observation_timestamp_.reset();
+}
+
+void EventBasedExponentialMovingAverage::AddSample(int64_t now, int sample) {
+  if (!last_observation_timestamp_.has_value()) {
+    value_ = sample;
+  } else {
+    // TODO(webrtc:11140): This should really be > (e.g not >=)
+    // but some pesky tests run with simulated clock and let
+    // samples arrive simultaneously!
+    RTC_DCHECK(now >= *last_observation_timestamp_);
+    // Variance gets computed after second sample.
+    int64_t age = now - *last_observation_timestamp_;
+    double e = exp(-age / tau_);
+    double alpha = e / (1 + e);
+    double one_minus_alpha = 1 - alpha;
+    double sample_diff = sample - value_;
+    value_ = one_minus_alpha * value_ + alpha * sample;
+    estimator_variance_ =
+        (one_minus_alpha * one_minus_alpha) * estimator_variance_ +
+        (alpha * alpha);
+    if (sample_variance_ == std::numeric_limits<double>::infinity()) {
+      // First variance.
+      sample_variance_ = sample_diff * sample_diff;
+    } else {
+      double new_variance = one_minus_alpha * sample_variance_ +
+                            alpha * sample_diff * sample_diff;
+      sample_variance_ = new_variance;
+    }
+  }
+  last_observation_timestamp_ = now;
+}
+
+double EventBasedExponentialMovingAverage::GetConfidenceInterval() const {
+  return ninetyfive_percent_confidence *
+         sqrt(sample_variance_ * estimator_variance_);
+}
+
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average.h b/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average.h
new file mode 100644
index 0000000000..a59fff7241
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average.h
@@ -0,0 +1,70 @@
+/*
+ *  Copyright 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 RTC_BASE_NUMERICS_EVENT_BASED_EXPONENTIAL_MOVING_AVERAGE_H_
+#define RTC_BASE_NUMERICS_EVENT_BASED_EXPONENTIAL_MOVING_AVERAGE_H_
+
+#include <cmath>
+#include <cstdint>
+#include <limits>
+#include "absl/types/optional.h"
+
+namespace rtc {
+
+/**
+ * This class implements exponential moving average for time series
+ * estimating both value, variance and variance of estimator based on
+ * https://en.wikipedia.org/w/index.php?title=Moving_average&section=9#Application_to_measuring_computer_performance
+ * with the additions from nisse@ added to
+ * https://en.wikipedia.org/wiki/Talk:Moving_average.
+ *
+ * A sample gets exponentially less weight so that it's 50%
+ * after `half_time` time units.
+ */
+class EventBasedExponentialMovingAverage {
+ public:
+  // `half_time` specifies how much weight will be given to old samples,
+  // see example above.
+  explicit EventBasedExponentialMovingAverage(int half_time);
+
+  void AddSample(int64_t now, int value);
+
+  double GetAverage() const { return value_; }
+  double GetVariance() const { return sample_variance_; }
+
+  // Compute 95% confidence interval assuming that
+  // - variance of samples are normal distributed.
+  // - variance of estimator is normal distributed.
+  //
+  // The returned values specifies the distance from the average,
+  // i.e if X = GetAverage(), m = GetConfidenceInterval()
+  // then a there is 95% likelihood that the observed variables is inside
+  // [ X +/- m ].
+  double GetConfidenceInterval() const;
+
+  // Reset
+  void Reset();
+
+  // Update the half_time.
+  // NOTE: resets estimate too.
+  void SetHalfTime(int half_time);
+
+ private:
+  double tau_;
+  double value_ = std::nan("uninit");
+  double sample_variance_ = std::numeric_limits<double>::infinity();
+  // This is the ratio between variance of the estimate and variance of samples.
+  double estimator_variance_ = 1;
+  absl::optional<int64_t> last_observation_timestamp_;
+};
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_NUMERICS_EVENT_BASED_EXPONENTIAL_MOVING_AVERAGE_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average_unittest.cc
new file mode 100644
index 0000000000..967be41213
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/event_based_exponential_moving_average_unittest.cc
@@ -0,0 +1,227 @@
+/*
+ *  Copyright 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.
+ */
+
+#include "rtc_base/numerics/event_based_exponential_moving_average.h"
+
+#include <cmath>
+
+#include "test/gtest.h"
+
+namespace {
+
+constexpr int kHalfTime = 500;
+constexpr double kError = 0.1;
+
+}  // namespace
+
+namespace rtc {
+
+TEST(EventBasedExponentialMovingAverageTest, NoValue) {
+  EventBasedExponentialMovingAverage average(kHalfTime);
+
+  EXPECT_TRUE(std::isnan(average.GetAverage()));
+  EXPECT_EQ(std::numeric_limits<double>::infinity(), average.GetVariance());
+  EXPECT_EQ(std::numeric_limits<double>::infinity(),
+            average.GetConfidenceInterval());
+}
+
+TEST(EventBasedExponentialMovingAverageTest, FirstValue) {
+  EventBasedExponentialMovingAverage average(kHalfTime);
+
+  int64_t time = 23;
+  constexpr int value = 1000;
+  average.AddSample(time, value);
+  EXPECT_NEAR(value, average.GetAverage(), kError);
+  EXPECT_EQ(std::numeric_limits<double>::infinity(), average.GetVariance());
+  EXPECT_EQ(std::numeric_limits<double>::infinity(),
+            average.GetConfidenceInterval());
+}
+
+TEST(EventBasedExponentialMovingAverageTest, Half) {
+  EventBasedExponentialMovingAverage average(kHalfTime);
+
+  int64_t time = 23;
+  constexpr int value = 1000;
+  average.AddSample(time, value);
+  average.AddSample(time + kHalfTime, 0);
+  EXPECT_NEAR(666.7, average.GetAverage(), kError);
+  EXPECT_NEAR(1000000, average.GetVariance(), kError);
+  EXPECT_NEAR(1460.9, average.GetConfidenceInterval(), kError);
+}
+
+TEST(EventBasedExponentialMovingAverageTest, Same) {
+  EventBasedExponentialMovingAverage average(kHalfTime);
+
+  int64_t time = 23;
+  constexpr int value = 1000;
+  average.AddSample(time, value);
+  average.AddSample(time + kHalfTime, value);
+  EXPECT_NEAR(value, average.GetAverage(), kError);
+  EXPECT_NEAR(0, average.GetVariance(), kError);
+  EXPECT_NEAR(0, average.GetConfidenceInterval(), kError);
+}
+
+TEST(EventBasedExponentialMovingAverageTest, Almost100) {
+  EventBasedExponentialMovingAverage average(kHalfTime);
+
+  int64_t time = 23;
+  constexpr int value = 100;
+  average.AddSample(time + 0 * kHalfTime, value - 10);
+  average.AddSample(time + 1 * kHalfTime, value + 10);
+  average.AddSample(time + 2 * kHalfTime, value - 15);
+  average.AddSample(time + 3 * kHalfTime, value + 15);
+  EXPECT_NEAR(100.2, average.GetAverage(), kError);
+  EXPECT_NEAR(372.6, average.GetVariance(), kError);
+  EXPECT_NEAR(19.7, average.GetConfidenceInterval(), kError);  // 100 +/- 20
+
+  average.AddSample(time + 4 * kHalfTime, value);
+  average.AddSample(time + 5 * kHalfTime, value);
+  average.AddSample(time + 6 * kHalfTime, value);
+  average.AddSample(time + 7 * kHalfTime, value);
+  EXPECT_NEAR(100.0, average.GetAverage(), kError);
+  EXPECT_NEAR(73.6, average.GetVariance(), kError);
+  EXPECT_NEAR(7.6, average.GetConfidenceInterval(), kError);  // 100 +/- 7
+}
+
+// Test that getting a value at X and another at X+1
+// is almost the same as getting another at X and a value at X+1.
+TEST(EventBasedExponentialMovingAverageTest, AlmostSameTime) {
+  int64_t time = 23;
+  constexpr int value = 100;
+
+  {
+    EventBasedExponentialMovingAverage average(kHalfTime);
+    average.AddSample(time + 0, value);
+    average.AddSample(time + 1, 0);
+    EXPECT_NEAR(50, average.GetAverage(), kError);
+    EXPECT_NEAR(10000, average.GetVariance(), kError);
+    EXPECT_NEAR(138.6, average.GetConfidenceInterval(),
+                kError);  // 50 +/- 138.6
+  }
+
+  {
+    EventBasedExponentialMovingAverage average(kHalfTime);
+    average.AddSample(time + 0, 0);
+    average.AddSample(time + 1, 100);
+    EXPECT_NEAR(50, average.GetAverage(), kError);
+    EXPECT_NEAR(10000, average.GetVariance(), kError);
+    EXPECT_NEAR(138.6, average.GetConfidenceInterval(),
+                kError);  // 50 +/- 138.6
+  }
+}
+
+// This test shows behavior of estimator with a half_time of 100.
+// It is unclear if these set of observations are representative
+// of any real world scenarios.
+TEST(EventBasedExponentialMovingAverageTest, NonUniformSamplesHalftime100) {
+  int64_t time = 23;
+  constexpr int value = 100;
+
+  {
+    // The observations at 100 and 101, are significantly close in
+    // time that the estimator returns approx. the average.
+    EventBasedExponentialMovingAverage average(100);
+    average.AddSample(time + 0, value);
+    average.AddSample(time + 100, value);
+    average.AddSample(time + 101, 0);
+    EXPECT_NEAR(50.2, average.GetAverage(), kError);
+    EXPECT_NEAR(86.2, average.GetConfidenceInterval(), kError);  // 50 +/- 86
+  }
+
+  {
+    EventBasedExponentialMovingAverage average(100);
+    average.AddSample(time + 0, value);
+    average.AddSample(time + 1, value);
+    average.AddSample(time + 100, 0);
+    EXPECT_NEAR(66.5, average.GetAverage(), kError);
+    EXPECT_NEAR(65.4, average.GetConfidenceInterval(), kError);  // 66 +/- 65
+  }
+
+  {
+    EventBasedExponentialMovingAverage average(100);
+    for (int i = 0; i < 10; i++) {
+      average.AddSample(time + i, value);
+    }
+    average.AddSample(time + 100, 0);
+    EXPECT_NEAR(65.3, average.GetAverage(), kError);
+    EXPECT_NEAR(59.1, average.GetConfidenceInterval(), kError);  // 55 +/- 59
+  }
+
+  {
+    EventBasedExponentialMovingAverage average(100);
+    average.AddSample(time + 0, 100);
+    for (int i = 90; i <= 100; i++) {
+      average.AddSample(time + i, 0);
+    }
+    EXPECT_NEAR(0.05, average.GetAverage(), kError);
+    EXPECT_NEAR(4.9, average.GetConfidenceInterval(), kError);  // 0 +/- 5
+  }
+}
+
+TEST(EventBasedExponentialMovingAverageTest, Reset) {
+  constexpr int64_t time = 23;
+  constexpr int value = 100;
+
+  EventBasedExponentialMovingAverage average(100);
+  EXPECT_TRUE(std::isnan(average.GetAverage()));
+  EXPECT_EQ(std::numeric_limits<double>::infinity(), average.GetVariance());
+  EXPECT_EQ(std::numeric_limits<double>::infinity(),
+            average.GetConfidenceInterval());
+
+  average.AddSample(time + 0, value);
+  average.AddSample(time + 100, value);
+  average.AddSample(time + 101, 0);
+  EXPECT_FALSE(std::isnan(average.GetAverage()));
+
+  average.Reset();
+  EXPECT_TRUE(std::isnan(average.GetAverage()));
+  EXPECT_EQ(std::numeric_limits<double>::infinity(), average.GetVariance());
+  EXPECT_EQ(std::numeric_limits<double>::infinity(),
+            average.GetConfidenceInterval());
+}
+
+// Test that SetHalfTime modifies behavior and resets average.
+TEST(EventBasedExponentialMovingAverageTest, SetHalfTime) {
+  constexpr int64_t time = 23;
+  constexpr int value = 100;
+
+  EventBasedExponentialMovingAverage average(100);
+
+  average.AddSample(time + 0, value);
+  average.AddSample(time + 100, 0);
+  EXPECT_NEAR(66.7, average.GetAverage(), kError);
+
+  average.SetHalfTime(1000);
+  EXPECT_TRUE(std::isnan(average.GetAverage()));
+  EXPECT_EQ(std::numeric_limits<double>::infinity(), average.GetVariance());
+  EXPECT_EQ(std::numeric_limits<double>::infinity(),
+            average.GetConfidenceInterval());
+
+  average.AddSample(time + 0, value);
+  average.AddSample(time + 100, 0);
+  EXPECT_NEAR(51.7, average.GetAverage(), kError);
+}
+
+TEST(EventBasedExponentialMovingAverageTest, SimultaneousSamples) {
+  constexpr int64_t time = 23;
+  constexpr int value = 100;
+
+  EventBasedExponentialMovingAverage average(100);
+
+  average.AddSample(time, value);
+  // This should really NOT be supported,
+  // i.e 2 samples with same timestamp.
+  // But there are tests running with simulated clock
+  // that produce this.
+  // TODO(webrtc:11140) : Fix those tests and remove this!
+  average.AddSample(time, value);
+}
+
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/event_rate_counter.cc b/third_party/libwebrtc/rtc_base/numerics/event_rate_counter.cc
new file mode 100644
index 0000000000..d7b7293918
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/event_rate_counter.cc
@@ -0,0 +1,49 @@
+/*
+ *  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.
+ */
+#include "rtc_base/numerics/event_rate_counter.h"
+
+#include <algorithm>
+
+namespace webrtc {
+
+void EventRateCounter::AddEvent(Timestamp event_time) {
+  if (first_time_.IsFinite())
+    interval_.AddSample(event_time - last_time_);
+  first_time_ = std::min(first_time_, event_time);
+  last_time_ = std::max(last_time_, event_time);
+  event_count_++;
+}
+
+void EventRateCounter::AddEvents(EventRateCounter other) {
+  first_time_ = std::min(first_time_, other.first_time_);
+  last_time_ = std::max(last_time_, other.last_time_);
+  event_count_ += other.event_count_;
+  interval_.AddSamples(other.interval_);
+}
+
+bool EventRateCounter::IsEmpty() const {
+  return first_time_ == last_time_;
+}
+
+double EventRateCounter::Rate() const {
+  if (event_count_ == 0)
+    return 0;
+  if (event_count_ == 1)
+    return NAN;
+  return (event_count_ - 1) / (last_time_ - first_time_).seconds<double>();
+}
+
+TimeDelta EventRateCounter::TotalDuration() const {
+  if (first_time_.IsInfinite()) {
+    return TimeDelta::Zero();
+  }
+  return last_time_ - first_time_;
+}
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/event_rate_counter.h b/third_party/libwebrtc/rtc_base/numerics/event_rate_counter.h
new file mode 100644
index 0000000000..60ec3ba416
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/event_rate_counter.h
@@ -0,0 +1,44 @@
+/*
+ *  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 RTC_BASE_NUMERICS_EVENT_RATE_COUNTER_H_
+#define RTC_BASE_NUMERICS_EVENT_RATE_COUNTER_H_
+
+#include "rtc_base/numerics/sample_stats.h"
+
+namespace webrtc {
+
+// Calculates statistics based on events. For example for computing frame rates.
+// Note that it doesn't provide any running statistics or reset funcitonality,
+// so it's mostly useful for end of call statistics.
+class EventRateCounter {
+ public:
+  // Adds an event based on it's `event_time` for correct updates of the
+  // interval statistics, each event must be added past the previous events.
+  void AddEvent(Timestamp event_time);
+  // Adds the events from `other`. Note that the interval stats won't be
+  // recalculated, only merged, so this is not equivalent to if the events would
+  // have been added to the same counter from the start.
+  void AddEvents(EventRateCounter other);
+  bool IsEmpty() const;
+  // Average number of events per second. Defaults to 0 for no events and NAN
+  // for one event.
+  double Rate() const;
+  SampleStats<TimeDelta>& interval() { return interval_; }
+  TimeDelta TotalDuration() const;
+  int Count() const { return event_count_; }
+
+ private:
+  Timestamp first_time_ = Timestamp::PlusInfinity();
+  Timestamp last_time_ = Timestamp::MinusInfinity();
+  int64_t event_count_ = 0;
+  SampleStats<TimeDelta> interval_;
+};
+}  // namespace webrtc
+#endif  // RTC_BASE_NUMERICS_EVENT_RATE_COUNTER_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/exp_filter.cc b/third_party/libwebrtc/rtc_base/numerics/exp_filter.cc
new file mode 100644
index 0000000000..a58250abc4
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/exp_filter.cc
@@ -0,0 +1,43 @@
+/*
+ *  Copyright (c) 2011 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 "rtc_base/numerics/exp_filter.h"
+
+#include <cmath>
+
+namespace rtc {
+
+const float ExpFilter::kValueUndefined = -1.0f;
+
+void ExpFilter::Reset(float alpha) {
+  alpha_ = alpha;
+  filtered_ = kValueUndefined;
+}
+
+float ExpFilter::Apply(float exp, float sample) {
+  if (filtered_ == kValueUndefined) {
+    // Initialize filtered value.
+    filtered_ = sample;
+  } else if (exp == 1.0) {
+    filtered_ = alpha_ * filtered_ + (1 - alpha_) * sample;
+  } else {
+    float alpha = std::pow(alpha_, exp);
+    filtered_ = alpha * filtered_ + (1 - alpha) * sample;
+  }
+  if (max_ != kValueUndefined && filtered_ > max_) {
+    filtered_ = max_;
+  }
+  return filtered_;
+}
+
+void ExpFilter::UpdateBase(float alpha) {
+  alpha_ = alpha;
+}
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/exp_filter.h b/third_party/libwebrtc/rtc_base/numerics/exp_filter.h
new file mode 100644
index 0000000000..6bded80d02
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/exp_filter.h
@@ -0,0 +1,48 @@
+/*
+ *  Copyright (c) 2011 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_EXP_FILTER_H_
+#define RTC_BASE_NUMERICS_EXP_FILTER_H_
+
+namespace rtc {
+
+// This class can be used, for example, for smoothing the result of bandwidth
+// estimation and packet loss estimation.
+
+class ExpFilter {
+ public:
+  static const float kValueUndefined;
+
+  explicit ExpFilter(float alpha, float max = kValueUndefined) : max_(max) {
+    Reset(alpha);
+  }
+
+  // Resets the filter to its initial state, and resets filter factor base to
+  // the given value `alpha`.
+  void Reset(float alpha);
+
+  // Applies the filter with a given exponent on the provided sample:
+  // y(k) = min(alpha_^ exp * y(k-1) + (1 - alpha_^ exp) * sample, max_).
+  float Apply(float exp, float sample);
+
+  // Returns current filtered value.
+  float filtered() const { return filtered_; }
+
+  // Changes the filter factor base to the given value `alpha`.
+  void UpdateBase(float alpha);
+
+ private:
+  float alpha_;     // Filter factor base.
+  float filtered_;  // Current filter output.
+  const float max_;
+};
+}  // namespace rtc
+
+#endif  // RTC_BASE_NUMERICS_EXP_FILTER_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/exp_filter_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/exp_filter_unittest.cc
new file mode 100644
index 0000000000..f5b436f1b9
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/exp_filter_unittest.cc
@@ -0,0 +1,72 @@
+/*
+ *  Copyright 2014 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 "rtc_base/numerics/exp_filter.h"
+
+#include <cmath>
+
+#include "test/gtest.h"
+
+namespace rtc {
+
+TEST(ExpFilterTest, FirstTimeOutputEqualInput) {
+  // No max value defined.
+  ExpFilter filter = ExpFilter(0.9f);
+  filter.Apply(100.0f, 10.0f);
+
+  // First time, first argument no effect.
+  double value = 10.0f;
+  EXPECT_FLOAT_EQ(value, filter.filtered());
+}
+
+TEST(ExpFilterTest, SecondTime) {
+  float value;
+
+  ExpFilter filter = ExpFilter(0.9f);
+  filter.Apply(100.0f, 10.0f);
+
+  // First time, first argument no effect.
+  value = 10.0f;
+
+  filter.Apply(10.0f, 20.0f);
+  float alpha = std::pow(0.9f, 10.0f);
+  value = alpha * value + (1.0f - alpha) * 20.0f;
+  EXPECT_FLOAT_EQ(value, filter.filtered());
+}
+
+TEST(ExpFilterTest, Reset) {
+  ExpFilter filter = ExpFilter(0.9f);
+  filter.Apply(100.0f, 10.0f);
+
+  filter.Reset(0.8f);
+  filter.Apply(100.0f, 1.0f);
+
+  // Become first time after a reset.
+  double value = 1.0f;
+  EXPECT_FLOAT_EQ(value, filter.filtered());
+}
+
+TEST(ExpfilterTest, OutputLimitedByMax) {
+  double value;
+
+  // Max value defined.
+  ExpFilter filter = ExpFilter(0.9f, 1.0f);
+  filter.Apply(100.0f, 10.0f);
+
+  // Limited to max value.
+  value = 1.0f;
+  EXPECT_EQ(value, filter.filtered());
+
+  filter.Apply(1.0f, 0.0f);
+  value = 0.9f * value;
+  EXPECT_FLOAT_EQ(value, filter.filtered());
+}
+
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.cc b/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.cc
new file mode 100644
index 0000000000..29d2341c85
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.cc
@@ -0,0 +1,79 @@
+/*
+ *  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.
+ */
+
+#include "rtc_base/numerics/histogram_percentile_counter.h"
+
+#include <algorithm>
+#include <cmath>
+
+#include "rtc_base/checks.h"
+
+namespace rtc {
+HistogramPercentileCounter::HistogramPercentileCounter(
+    uint32_t long_tail_boundary)
+    : histogram_low_(size_t{long_tail_boundary}),
+      long_tail_boundary_(long_tail_boundary),
+      total_elements_(0),
+      total_elements_low_(0) {}
+
+HistogramPercentileCounter::~HistogramPercentileCounter() = default;
+
+void HistogramPercentileCounter::Add(const HistogramPercentileCounter& other) {
+  for (uint32_t value = 0; value < other.long_tail_boundary_; ++value) {
+    Add(value, other.histogram_low_[value]);
+  }
+  for (const auto& it : histogram_high_) {
+    Add(it.first, it.second);
+  }
+}
+
+void HistogramPercentileCounter::Add(uint32_t value, size_t count) {
+  if (value < long_tail_boundary_) {
+    histogram_low_[value] += count;
+    total_elements_low_ += count;
+  } else {
+    histogram_high_[value] += count;
+  }
+  total_elements_ += count;
+}
+
+void HistogramPercentileCounter::Add(uint32_t value) {
+  Add(value, 1);
+}
+
+absl::optional<uint32_t> HistogramPercentileCounter::GetPercentile(
+    float fraction) {
+  RTC_CHECK_LE(fraction, 1.0);
+  RTC_CHECK_GE(fraction, 0.0);
+  if (total_elements_ == 0)
+    return absl::nullopt;
+  size_t elements_to_skip = static_cast<size_t>(
+      std::max(0.0f, std::ceil(total_elements_ * fraction) - 1));
+  if (elements_to_skip >= total_elements_)
+    elements_to_skip = total_elements_ - 1;
+  if (elements_to_skip < total_elements_low_) {
+    for (uint32_t value = 0; value < long_tail_boundary_; ++value) {
+      if (elements_to_skip < histogram_low_[value])
+        return value;
+      elements_to_skip -= histogram_low_[value];
+    }
+  } else {
+    elements_to_skip -= total_elements_low_;
+    for (const auto& it : histogram_high_) {
+      if (elements_to_skip < it.second)
+        return it.first;
+      elements_to_skip -= it.second;
+    }
+  }
+  RTC_DCHECK_NOTREACHED();
+  return absl::nullopt;
+}
+
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.h b/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.h
new file mode 100644
index 0000000000..4787f2ef98
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter.h
@@ -0,0 +1,45 @@
+/*
+ *  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_
diff --git a/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter_unittest.cc
new file mode 100644
index 0000000000..fc36b59208
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/histogram_percentile_counter_unittest.cc
@@ -0,0 +1,44 @@
+/*
+ *  Copyright 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.
+ */
+
+#include "rtc_base/numerics/histogram_percentile_counter.h"
+
+#include <cstdint>
+#include <utility>
+#include <vector>
+
+#include "test/gtest.h"
+
+TEST(HistogramPercentileCounterTest, ReturnsCorrectPercentiles) {
+  rtc::HistogramPercentileCounter counter(10);
+  const std::vector<int> kTestValues = {1,  2,  3,  4,  5,  6,  7,  8,  9,  10,
+                                        11, 12, 13, 14, 15, 16, 17, 18, 19, 20};
+
+  EXPECT_FALSE(counter.GetPercentile(0.5f));
+  // Pairs of {fraction, percentile value} computed by hand
+  // for `kTestValues`.
+  const std::vector<std::pair<float, uint32_t>> kTestPercentiles = {
+      {0.0f, 1},   {0.01f, 1},  {0.5f, 10}, {0.9f, 18},
+      {0.95f, 19}, {0.99f, 20}, {1.0f, 20}};
+  for (int value : kTestValues) {
+    counter.Add(value);
+  }
+  for (const auto& test_percentile : kTestPercentiles) {
+    EXPECT_EQ(test_percentile.second,
+              counter.GetPercentile(test_percentile.first).value_or(0));
+  }
+}
+
+TEST(HistogramPercentileCounterTest, HandlesEmptySequence) {
+  rtc::HistogramPercentileCounter counter(10);
+  EXPECT_FALSE(counter.GetPercentile(0.5f));
+  counter.Add(1u);
+  EXPECT_TRUE(counter.GetPercentile(0.5f));
+}
diff --git a/third_party/libwebrtc/rtc_base/numerics/math_utils.h b/third_party/libwebrtc/rtc_base/numerics/math_utils.h
new file mode 100644
index 0000000000..5482cec6e5
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/math_utils.h
@@ -0,0 +1,75 @@
+/*
+ *  Copyright 2005 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 API_NUMERICS_MATH_UTILS_H_
+#define API_NUMERICS_MATH_UTILS_H_
+
+#include <limits>
+#include <type_traits>
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+namespace webrtc_impl {
+// Given two numbers `x` and `y` such that x >= y, computes the difference
+// x - y without causing undefined behavior due to signed overflow.
+template <typename T>
+typename std::make_unsigned<T>::type unsigned_difference(T x, T y) {
+  static_assert(
+      std::is_signed<T>::value,
+      "Function unsigned_difference is only meaningful for signed types.");
+  RTC_DCHECK_GE(x, y);
+  typedef typename std::make_unsigned<T>::type unsigned_type;
+  // int -> unsigned conversion repeatedly adds UINT_MAX + 1 until the number
+  // can be represented as an unsigned. Since we know that the actual
+  // difference x - y can be represented as an unsigned, it is sufficient to
+  // compute the difference modulo UINT_MAX + 1, i.e using unsigned arithmetic.
+  return static_cast<unsigned_type>(x) - static_cast<unsigned_type>(y);
+}
+
+// Provide neutral element with respect to min().
+// Typically used as an initial value for running minimum.
+template <typename T,
+          typename std::enable_if<std::numeric_limits<T>::has_infinity>::type* =
+              nullptr>
+constexpr T infinity_or_max() {
+  return std::numeric_limits<T>::infinity();
+}
+
+template <typename T,
+          typename std::enable_if<
+              !std::numeric_limits<T>::has_infinity>::type* = nullptr>
+constexpr T infinity_or_max() {
+  // Fallback to max().
+  return std::numeric_limits<T>::max();
+}
+
+// Provide neutral element with respect to max().
+// Typically used as an initial value for running maximum.
+template <typename T,
+          typename std::enable_if<std::numeric_limits<T>::has_infinity>::type* =
+              nullptr>
+constexpr T minus_infinity_or_min() {
+  static_assert(std::is_signed<T>::value, "Unsupported. Please open a bug.");
+  return -std::numeric_limits<T>::infinity();
+}
+
+template <typename T,
+          typename std::enable_if<
+              !std::numeric_limits<T>::has_infinity>::type* = nullptr>
+constexpr T minus_infinity_or_min() {
+  // Fallback to min().
+  return std::numeric_limits<T>::min();
+}
+
+}  // namespace webrtc_impl
+}  // namespace webrtc
+
+#endif  // API_NUMERICS_MATH_UTILS_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/mod_ops.h b/third_party/libwebrtc/rtc_base/numerics/mod_ops.h
new file mode 100644
index 0000000000..65618b4876
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/mod_ops.h
@@ -0,0 +1,142 @@
+/*
+ *  Copyright (c) 2016 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_MOD_OPS_H_
+#define RTC_BASE_NUMERICS_MOD_OPS_H_
+
+#include <algorithm>
+#include <type_traits>
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+
+template <unsigned long M>                                    // NOLINT
+inline unsigned long Add(unsigned long a, unsigned long b) {  // NOLINT
+  RTC_DCHECK_LT(a, M);
+  unsigned long t = M - b % M;  // NOLINT
+  unsigned long res = a - t;    // NOLINT
+  if (t > a)
+    return res + M;
+  return res;
+}
+
+template <unsigned long M>                                         // NOLINT
+inline unsigned long Subtract(unsigned long a, unsigned long b) {  // NOLINT
+  RTC_DCHECK_LT(a, M);
+  unsigned long sub = b % M;  // NOLINT
+  if (a < sub)
+    return M - (sub - a);
+  return a - sub;
+}
+
+// Calculates the forward difference between two wrapping numbers.
+//
+// Example:
+// uint8_t x = 253;
+// uint8_t y = 2;
+//
+// ForwardDiff(x, y) == 5
+//
+//   252   253   254   255    0     1     2     3
+// #################################################
+// |     |  x  |     |     |     |     |  y  |     |
+// #################################################
+//          |----->----->----->----->----->
+//
+// ForwardDiff(y, x) == 251
+//
+//   252   253   254   255    0     1     2     3
+// #################################################
+// |     |  x  |     |     |     |     |  y  |     |
+// #################################################
+// -->----->                              |----->---
+//
+// If M > 0 then wrapping occurs at M, if M == 0 then wrapping occurs at the
+// largest value representable by T.
+template <typename T, T M>
+inline typename std::enable_if<(M > 0), T>::type ForwardDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  RTC_DCHECK_LT(a, M);
+  RTC_DCHECK_LT(b, M);
+  return a <= b ? b - a : M - (a - b);
+}
+
+template <typename T, T M>
+inline typename std::enable_if<(M == 0), T>::type ForwardDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  return b - a;
+}
+
+template <typename T>
+inline T ForwardDiff(T a, T b) {
+  return ForwardDiff<T, 0>(a, b);
+}
+
+// Calculates the reverse difference between two wrapping numbers.
+//
+// Example:
+// uint8_t x = 253;
+// uint8_t y = 2;
+//
+// ReverseDiff(y, x) == 5
+//
+//   252   253   254   255    0     1     2     3
+// #################################################
+// |     |  x  |     |     |     |     |  y  |     |
+// #################################################
+//          <-----<-----<-----<-----<-----|
+//
+// ReverseDiff(x, y) == 251
+//
+//   252   253   254   255    0     1     2     3
+// #################################################
+// |     |  x  |     |     |     |     |  y  |     |
+// #################################################
+// ---<-----|                             |<-----<--
+//
+// If M > 0 then wrapping occurs at M, if M == 0 then wrapping occurs at the
+// largest value representable by T.
+template <typename T, T M>
+inline typename std::enable_if<(M > 0), T>::type ReverseDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  RTC_DCHECK_LT(a, M);
+  RTC_DCHECK_LT(b, M);
+  return b <= a ? a - b : M - (b - a);
+}
+
+template <typename T, T M>
+inline typename std::enable_if<(M == 0), T>::type ReverseDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  return a - b;
+}
+
+template <typename T>
+inline T ReverseDiff(T a, T b) {
+  return ReverseDiff<T, 0>(a, b);
+}
+
+// Calculates the minimum distance between to wrapping numbers.
+//
+// The minimum distance is defined as min(ForwardDiff(a, b), ReverseDiff(a, b))
+template <typename T, T M = 0>
+inline T MinDiff(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  return std::min(ForwardDiff<T, M>(a, b), ReverseDiff<T, M>(a, b));
+}
+
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_MOD_OPS_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/mod_ops_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/mod_ops_unittest.cc
new file mode 100644
index 0000000000..3bd20345a7
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/mod_ops_unittest.cc
@@ -0,0 +1,159 @@
+/*
+ *  Copyright (c) 2016 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 "rtc_base/numerics/mod_ops.h"
+
+#include <stdint.h>
+
+#include "test/gtest.h"
+
+namespace webrtc {
+class TestModOps : public ::testing::Test {
+ protected:
+  // Can't use std::numeric_limits<unsigned long>::max() since
+  // MSVC doesn't support constexpr.
+  static const unsigned long ulmax = ~0ul;  // NOLINT
+};
+
+TEST_F(TestModOps, Add) {
+  const int D = 100;
+  ASSERT_EQ(1u, Add<D>(0, 1));
+  ASSERT_EQ(0u, Add<D>(0, D));
+  for (int i = 0; i < D; ++i)
+    ASSERT_EQ(0u, Add<D>(i, D - i));
+
+  int t = 37;
+  uint8_t a = t;
+  for (int i = 0; i < 256; ++i) {
+    ASSERT_EQ(a, static_cast<uint8_t>(t));
+    t = Add<256>(t, 1);
+    ++a;
+  }
+}
+
+TEST_F(TestModOps, AddLarge) {
+  const unsigned long D = ulmax - 10ul;  // NOLINT
+  unsigned long l = D - 1ul;             // NOLINT
+  ASSERT_EQ(D - 2ul, Add<D>(l, l));
+  ASSERT_EQ(9ul, Add<D>(l, ulmax));
+  ASSERT_EQ(10ul, Add<D>(0ul, ulmax));
+}
+
+TEST_F(TestModOps, Subtract) {
+  const int D = 100;
+  ASSERT_EQ(99u, Subtract<D>(0, 1));
+  ASSERT_EQ(0u, Subtract<D>(0, D));
+  for (int i = 0; i < D; ++i)
+    ASSERT_EQ(0u, Subtract<D>(i, D + i));
+
+  int t = 37;
+  uint8_t a = t;
+  for (int i = 0; i < 256; ++i) {
+    ASSERT_EQ(a, static_cast<uint8_t>(t));
+    t = Subtract<256>(t, 1);
+    --a;
+  }
+}
+
+TEST_F(TestModOps, SubtractLarge) {
+  // NOLINTNEXTLINE
+  const unsigned long D = ulmax - 10ul;  // NOLINT
+  unsigned long l = D - 1ul;             // NOLINT
+  ASSERT_EQ(0ul, Subtract<D>(l, l));
+  ASSERT_EQ(D - 11ul, Subtract<D>(l, ulmax));
+  ASSERT_EQ(D - 10ul, Subtract<D>(0ul, ulmax));
+}
+
+TEST_F(TestModOps, ForwardDiff) {
+  ASSERT_EQ(0u, ForwardDiff(4711u, 4711u));
+
+  uint8_t x = 0;
+  uint8_t y = 255;
+  for (int i = 0; i < 256; ++i) {
+    ASSERT_EQ(255u, ForwardDiff(x, y));
+    ++x;
+    ++y;
+  }
+
+  int yi = 255;
+  for (int i = 0; i < 256; ++i) {
+    ASSERT_EQ(255u, ForwardDiff<uint8_t>(x, yi));
+    ++x;
+    ++yi;
+  }
+}
+
+TEST_F(TestModOps, ForwardDiffWithDivisor) {
+  ASSERT_EQ(122, (ForwardDiff<uint8_t, 123>(0, 122)));
+  ASSERT_EQ(0, (ForwardDiff<uint8_t, 123>(122, 122)));
+  ASSERT_EQ(122, (ForwardDiff<uint8_t, 123>(1, 0)));
+  ASSERT_EQ(0, (ForwardDiff<uint8_t, 123>(0, 0)));
+  ASSERT_EQ(1, (ForwardDiff<uint8_t, 123>(122, 0)));
+}
+
+TEST_F(TestModOps, ReverseDiff) {
+  ASSERT_EQ(0u, ReverseDiff(4711u, 4711u));
+
+  uint8_t x = 0;
+  uint8_t y = 255;
+  for (int i = 0; i < 256; ++i) {
+    ASSERT_EQ(1u, ReverseDiff(x, y));
+    ++x;
+    ++y;
+  }
+
+  int yi = 255;
+  for (int i = 0; i < 256; ++i) {
+    ASSERT_EQ(1u, ReverseDiff<uint8_t>(x, yi));
+    ++x;
+    ++yi;
+  }
+}
+
+TEST_F(TestModOps, ReverseDiffWithDivisor) {
+  ASSERT_EQ(1, (ReverseDiff<uint8_t, 123>(0, 122)));
+  ASSERT_EQ(0, (ReverseDiff<uint8_t, 123>(122, 122)));
+  ASSERT_EQ(1, (ReverseDiff<uint8_t, 123>(1, 0)));
+  ASSERT_EQ(0, (ReverseDiff<uint8_t, 123>(0, 0)));
+  ASSERT_EQ(122, (ReverseDiff<uint8_t, 123>(122, 0)));
+}
+
+TEST_F(TestModOps, MinDiff) {
+  for (uint16_t i = 0; i < 256; ++i) {
+    ASSERT_EQ(0, MinDiff<uint8_t>(i, i));
+    ASSERT_EQ(1, MinDiff<uint8_t>(i - 1, i));
+    ASSERT_EQ(1, MinDiff<uint8_t>(i + 1, i));
+  }
+
+  for (uint8_t i = 0; i < 128; ++i)
+    ASSERT_EQ(i, MinDiff<uint8_t>(0, i));
+
+  for (uint8_t i = 0; i < 128; ++i)
+    ASSERT_EQ(128 - i, MinDiff<uint8_t>(0, 128 + i));
+}
+
+TEST_F(TestModOps, MinDiffWitDivisor) {
+  ASSERT_EQ(5u, (MinDiff<uint8_t, 11>(0, 5)));
+  ASSERT_EQ(5u, (MinDiff<uint8_t, 11>(0, 6)));
+  ASSERT_EQ(5u, (MinDiff<uint8_t, 11>(5, 0)));
+  ASSERT_EQ(5u, (MinDiff<uint8_t, 11>(6, 0)));
+
+  const uint16_t D = 4711;
+
+  for (uint16_t i = 0; i < D / 2; ++i)
+    ASSERT_EQ(i, (MinDiff<uint16_t, D>(0, i)));
+
+  ASSERT_EQ(D / 2, (MinDiff<uint16_t, D>(0, D / 2)));
+
+  for (uint16_t i = 0; i < D / 2; ++i)
+    ASSERT_EQ(D / 2 - i, (MinDiff<uint16_t, D>(0, D / 2 - i)));
+}
+
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/moving_average.cc b/third_party/libwebrtc/rtc_base/numerics/moving_average.cc
new file mode 100644
index 0000000000..c825839227
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/moving_average.cc
@@ -0,0 +1,60 @@
+/*
+ *  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 "rtc_base/numerics/moving_average.h"
+
+#include <algorithm>
+
+#include "rtc_base/checks.h"
+
+namespace rtc {
+
+MovingAverage::MovingAverage(size_t window_size) : history_(window_size, 0) {
+  // Limit window size to avoid overflow.
+  RTC_DCHECK_LE(window_size, (int64_t{1} << 32) - 1);
+}
+MovingAverage::~MovingAverage() = default;
+
+void MovingAverage::AddSample(int sample) {
+  count_++;
+  size_t index = count_ % history_.size();
+  if (count_ > history_.size())
+    sum_ -= history_[index];
+  sum_ += sample;
+  history_[index] = sample;
+}
+
+absl::optional<int> MovingAverage::GetAverageRoundedDown() const {
+  if (count_ == 0)
+    return absl::nullopt;
+  return sum_ / Size();
+}
+
+absl::optional<int> MovingAverage::GetAverageRoundedToClosest() const {
+  if (count_ == 0)
+    return absl::nullopt;
+  return (sum_ + Size() / 2) / Size();
+}
+
+absl::optional<double> MovingAverage::GetUnroundedAverage() const {
+  if (count_ == 0)
+    return absl::nullopt;
+  return sum_ / static_cast<double>(Size());
+}
+
+void MovingAverage::Reset() {
+  count_ = 0;
+  sum_ = 0;
+}
+
+size_t MovingAverage::Size() const {
+  return std::min(count_, history_.size());
+}
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/moving_average.h b/third_party/libwebrtc/rtc_base/numerics/moving_average.h
new file mode 100644
index 0000000000..41ce60348e
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/moving_average.h
@@ -0,0 +1,66 @@
+/*
+ *  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.
+ */
+
+#ifndef RTC_BASE_NUMERICS_MOVING_AVERAGE_H_
+#define RTC_BASE_NUMERICS_MOVING_AVERAGE_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <vector>
+
+#include "absl/types/optional.h"
+
+namespace rtc {
+
+// Calculates average over fixed size window. If there are less than window
+// size elements, calculates average of all inserted so far elements.
+//
+class MovingAverage {
+ public:
+  // Maximum supported window size is 2^32 - 1.
+  explicit MovingAverage(size_t window_size);
+  ~MovingAverage();
+  // MovingAverage is neither copyable nor movable.
+  MovingAverage(const MovingAverage&) = delete;
+  MovingAverage& operator=(const MovingAverage&) = delete;
+
+  // Adds new sample. If the window is full, the oldest element is pushed out.
+  void AddSample(int sample);
+
+  // Returns rounded down average of last `window_size` elements or all
+  // elements if there are not enough of them. Returns nullopt if there were
+  // no elements added.
+  absl::optional<int> GetAverageRoundedDown() const;
+
+  // Same as above but rounded to the closest integer.
+  absl::optional<int> GetAverageRoundedToClosest() const;
+
+  // Returns unrounded average over the window.
+  absl::optional<double> GetUnroundedAverage() const;
+
+  // Resets to the initial state before any elements were added.
+  void Reset();
+
+  // Returns number of elements in the window.
+  size_t Size() const;
+
+ private:
+  // Total number of samples added to the class since last reset.
+  size_t count_ = 0;
+  // Sum of the samples in the moving window.
+  int64_t sum_ = 0;
+  // Circular buffer for all the samples in the moving window.
+  // Size is always `window_size`
+  std::vector<int> history_;
+};
+
+}  // namespace rtc
+#endif  // RTC_BASE_NUMERICS_MOVING_AVERAGE_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/moving_average_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/moving_average_unittest.cc
new file mode 100644
index 0000000000..9bc9a1aef8
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/moving_average_unittest.cc
@@ -0,0 +1,87 @@
+/*
+ *  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 "rtc_base/numerics/moving_average.h"
+
+#include "test/gtest.h"
+
+namespace test {
+
+TEST(MovingAverageTest, EmptyAverage) {
+  rtc::MovingAverage moving_average(1);
+  EXPECT_EQ(0u, moving_average.Size());
+  EXPECT_EQ(absl::nullopt, moving_average.GetAverageRoundedDown());
+}
+
+// Test single value.
+TEST(MovingAverageTest, OneElement) {
+  rtc::MovingAverage moving_average(1);
+  moving_average.AddSample(3);
+  EXPECT_EQ(1u, moving_average.Size());
+  EXPECT_EQ(3, *moving_average.GetAverageRoundedDown());
+}
+
+TEST(MovingAverageTest, GetAverage) {
+  rtc::MovingAverage moving_average(1024);
+  moving_average.AddSample(1);
+  moving_average.AddSample(1);
+  moving_average.AddSample(3);
+  moving_average.AddSample(3);
+  EXPECT_EQ(*moving_average.GetAverageRoundedDown(), 2);
+  EXPECT_EQ(*moving_average.GetAverageRoundedToClosest(), 2);
+}
+
+TEST(MovingAverageTest, GetAverageRoundedDownRounds) {
+  rtc::MovingAverage moving_average(1024);
+  moving_average.AddSample(1);
+  moving_average.AddSample(2);
+  moving_average.AddSample(2);
+  moving_average.AddSample(2);
+  EXPECT_EQ(*moving_average.GetAverageRoundedDown(), 1);
+}
+
+TEST(MovingAverageTest, GetAverageRoundedToClosestRounds) {
+  rtc::MovingAverage moving_average(1024);
+  moving_average.AddSample(1);
+  moving_average.AddSample(2);
+  moving_average.AddSample(2);
+  moving_average.AddSample(2);
+  EXPECT_EQ(*moving_average.GetAverageRoundedToClosest(), 2);
+}
+
+TEST(MovingAverageTest, Reset) {
+  rtc::MovingAverage moving_average(5);
+  moving_average.AddSample(1);
+  EXPECT_EQ(1, *moving_average.GetAverageRoundedDown());
+  EXPECT_EQ(1, *moving_average.GetAverageRoundedToClosest());
+
+  moving_average.Reset();
+
+  EXPECT_FALSE(moving_average.GetAverageRoundedDown());
+  moving_average.AddSample(10);
+  EXPECT_EQ(10, *moving_average.GetAverageRoundedDown());
+  EXPECT_EQ(10, *moving_average.GetAverageRoundedToClosest());
+}
+
+TEST(MovingAverageTest, ManySamples) {
+  rtc::MovingAverage moving_average(10);
+  for (int i = 1; i < 11; i++) {
+    moving_average.AddSample(i);
+  }
+  EXPECT_EQ(*moving_average.GetAverageRoundedDown(), 5);
+  EXPECT_EQ(*moving_average.GetAverageRoundedToClosest(), 6);
+  for (int i = 1; i < 2001; i++) {
+    moving_average.AddSample(i);
+  }
+  EXPECT_EQ(*moving_average.GetAverageRoundedDown(), 1995);
+  EXPECT_EQ(*moving_average.GetAverageRoundedToClosest(), 1996);
+}
+
+}  // namespace test
diff --git a/third_party/libwebrtc/rtc_base/numerics/moving_max_counter.h b/third_party/libwebrtc/rtc_base/numerics/moving_max_counter.h
new file mode 100644
index 0000000000..5eb45d392b
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/moving_max_counter.h
@@ -0,0 +1,118 @@
+/*
+ *  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_MOVING_MAX_COUNTER_H_
+#define RTC_BASE_NUMERICS_MOVING_MAX_COUNTER_H_
+
+#include <stdint.h>
+
+#include <deque>
+#include <limits>
+#include <utility>
+
+#include "absl/types/optional.h"
+#include "rtc_base/checks.h"
+
+namespace rtc {
+
+// Implements moving max: can add samples to it and calculate maximum over some
+// fixed moving window.
+//
+// Window size is configured at constructor.
+// Samples can be added with `Add()` and max over current window is returned by
+// `MovingMax`. `current_time_ms` in successive calls to Add and MovingMax
+// should never decrease as if it's a wallclock time.
+template <class T>
+class MovingMaxCounter {
+ public:
+  explicit MovingMaxCounter(int64_t window_length_ms);
+
+  MovingMaxCounter(const MovingMaxCounter&) = delete;
+  MovingMaxCounter& operator=(const MovingMaxCounter&) = delete;
+
+  // Advances the current time, and adds a new sample. The new current time must
+  // be at least as large as the old current time.
+  void Add(const T& sample, int64_t current_time_ms);
+  // Advances the current time, and returns the maximum sample in the time
+  // window ending at the current time. The new current time must be at least as
+  // large as the old current time.
+  absl::optional<T> Max(int64_t current_time_ms);
+  void Reset();
+
+ private:
+  // Throws out obsolete samples.
+  void RollWindow(int64_t new_time_ms);
+  const int64_t window_length_ms_;
+  // This deque stores (timestamp, sample) pairs in chronological order; new
+  // pairs are only ever added at the end. However, because they can't affect
+  // the Max() calculation, pairs older than window_length_ms_ are discarded,
+  // and if an older pair has a sample that's smaller than that of a younger
+  // pair, the older pair is discarded. As a result, the sequence of timestamps
+  // is strictly increasing, and the sequence of samples is strictly decreasing.
+  std::deque<std::pair<int64_t, T>> samples_;
+#if RTC_DCHECK_IS_ON
+  int64_t last_call_time_ms_ = std::numeric_limits<int64_t>::min();
+#endif
+};
+
+template <class T>
+MovingMaxCounter<T>::MovingMaxCounter(int64_t window_length_ms)
+    : window_length_ms_(window_length_ms) {}
+
+template <class T>
+void MovingMaxCounter<T>::Add(const T& sample, int64_t current_time_ms) {
+  RollWindow(current_time_ms);
+  // Remove samples that will never be maximum in any window: newly added sample
+  // will always be in all windows the previous samples are. Thus, smaller or
+  // equal samples could be removed. This will maintain the invariant - deque
+  // contains strictly decreasing sequence of values.
+  while (!samples_.empty() && samples_.back().second <= sample) {
+    samples_.pop_back();
+  }
+  // Add the new sample but only if there's no existing sample at the same time.
+  // Due to checks above, the already existing element will be larger, so the
+  // new sample will never be the maximum in any window.
+  if (samples_.empty() || samples_.back().first < current_time_ms) {
+    samples_.emplace_back(std::make_pair(current_time_ms, sample));
+  }
+}
+
+template <class T>
+absl::optional<T> MovingMaxCounter<T>::Max(int64_t current_time_ms) {
+  RollWindow(current_time_ms);
+  absl::optional<T> res;
+  if (!samples_.empty()) {
+    res.emplace(samples_.front().second);
+  }
+  return res;
+}
+
+template <class T>
+void MovingMaxCounter<T>::Reset() {
+  samples_.clear();
+}
+
+template <class T>
+void MovingMaxCounter<T>::RollWindow(int64_t new_time_ms) {
+#if RTC_DCHECK_IS_ON
+  RTC_DCHECK_GE(new_time_ms, last_call_time_ms_);
+  last_call_time_ms_ = new_time_ms;
+#endif
+  const int64_t window_begin_ms = new_time_ms - window_length_ms_;
+  auto it = samples_.begin();
+  while (it != samples_.end() && it->first < window_begin_ms) {
+    ++it;
+  }
+  samples_.erase(samples_.begin(), it);
+}
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_NUMERICS_MOVING_MAX_COUNTER_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/moving_max_counter_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/moving_max_counter_unittest.cc
new file mode 100644
index 0000000000..0e3195f467
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/moving_max_counter_unittest.cc
@@ -0,0 +1,58 @@
+/*
+ *  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.
+ */
+
+#include "rtc_base/numerics/moving_max_counter.h"
+
+#include "test/gtest.h"
+
+TEST(MovingMaxCounter, ReportsMaximumInTheWindow) {
+  rtc::MovingMaxCounter<int> counter(100);
+  counter.Add(1, 1);
+  EXPECT_EQ(counter.Max(1), 1);
+  counter.Add(2, 30);
+  EXPECT_EQ(counter.Max(30), 2);
+  counter.Add(100, 60);
+  EXPECT_EQ(counter.Max(60), 100);
+  counter.Add(4, 70);
+  EXPECT_EQ(counter.Max(70), 100);
+  counter.Add(5, 90);
+  EXPECT_EQ(counter.Max(90), 100);
+}
+
+TEST(MovingMaxCounter, IgnoresOldElements) {
+  rtc::MovingMaxCounter<int> counter(100);
+  counter.Add(1, 1);
+  counter.Add(2, 30);
+  counter.Add(100, 60);
+  counter.Add(4, 70);
+  counter.Add(5, 90);
+  EXPECT_EQ(counter.Max(160), 100);
+  // 100 is now out of the window. Next maximum is 5.
+  EXPECT_EQ(counter.Max(161), 5);
+}
+
+TEST(MovingMaxCounter, HandlesEmptyWindow) {
+  rtc::MovingMaxCounter<int> counter(100);
+  counter.Add(123, 1);
+  EXPECT_TRUE(counter.Max(101).has_value());
+  EXPECT_FALSE(counter.Max(102).has_value());
+}
+
+TEST(MovingMaxCounter, HandlesSamplesWithEqualTimestamps) {
+  rtc::MovingMaxCounter<int> counter(100);
+  counter.Add(2, 30);
+  EXPECT_EQ(counter.Max(30), 2);
+  counter.Add(5, 30);
+  EXPECT_EQ(counter.Max(30), 5);
+  counter.Add(4, 30);
+  EXPECT_EQ(counter.Max(30), 5);
+  counter.Add(1, 90);
+  EXPECT_EQ(counter.Max(150), 1);
+}
diff --git a/third_party/libwebrtc/rtc_base/numerics/moving_percentile_filter.h b/third_party/libwebrtc/rtc_base/numerics/moving_percentile_filter.h
new file mode 100644
index 0000000000..d68814a25b
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/moving_percentile_filter.h
@@ -0,0 +1,103 @@
+/*
+ *  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_MOVING_PERCENTILE_FILTER_H_
+#define RTC_BASE_NUMERICS_MOVING_PERCENTILE_FILTER_H_
+
+#include <stddef.h>
+
+#include <cstddef>
+#include <list>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/percentile_filter.h"
+
+namespace webrtc {
+
+// Class to efficiently get moving percentile filter from a stream of samples.
+template <typename T>
+class MovingPercentileFilter {
+ public:
+  // Construct filter. `percentile` defines what percentile to track and
+  // `window_size` is how many latest samples are stored for finding the
+  // percentile. `percentile` must be between 0.0 and 1.0 (inclusive) and
+  // `window_size` must be greater than 0.
+  MovingPercentileFilter(float percentile, size_t window_size);
+
+  MovingPercentileFilter(const MovingPercentileFilter&) = delete;
+  MovingPercentileFilter& operator=(const MovingPercentileFilter&) = delete;
+
+  // Insert a new sample.
+  void Insert(const T& value);
+
+  // Removes all samples;
+  void Reset();
+
+  // Get percentile over the latest window.
+  T GetFilteredValue() const;
+
+  // The number of samples that are currently stored.
+  size_t GetNumberOfSamplesStored() const;
+
+ private:
+  PercentileFilter<T> percentile_filter_;
+  std::list<T> samples_;
+  size_t samples_stored_;
+  const size_t window_size_;
+};
+
+// Convenience type for the common median case.
+template <typename T>
+class MovingMedianFilter : public MovingPercentileFilter<T> {
+ public:
+  explicit MovingMedianFilter(size_t window_size)
+      : MovingPercentileFilter<T>(0.5f, window_size) {}
+};
+
+template <typename T>
+MovingPercentileFilter<T>::MovingPercentileFilter(float percentile,
+                                                  size_t window_size)
+    : percentile_filter_(percentile),
+      samples_stored_(0),
+      window_size_(window_size) {
+  RTC_CHECK_GT(window_size, 0);
+}
+
+template <typename T>
+void MovingPercentileFilter<T>::Insert(const T& value) {
+  percentile_filter_.Insert(value);
+  samples_.emplace_back(value);
+  ++samples_stored_;
+  if (samples_stored_ > window_size_) {
+    percentile_filter_.Erase(samples_.front());
+    samples_.pop_front();
+    --samples_stored_;
+  }
+}
+
+template <typename T>
+T MovingPercentileFilter<T>::GetFilteredValue() const {
+  return percentile_filter_.GetPercentileValue();
+}
+
+template <typename T>
+void MovingPercentileFilter<T>::Reset() {
+  percentile_filter_.Reset();
+  samples_.clear();
+  samples_stored_ = 0;
+}
+
+template <typename T>
+size_t MovingPercentileFilter<T>::GetNumberOfSamplesStored() const {
+  return samples_stored_;
+}
+
+}  // namespace webrtc
+#endif  // RTC_BASE_NUMERICS_MOVING_PERCENTILE_FILTER_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/moving_percentile_filter_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/moving_percentile_filter_unittest.cc
new file mode 100644
index 0000000000..30c0ebb23d
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/moving_percentile_filter_unittest.cc
@@ -0,0 +1,86 @@
+/*
+ *  Copyright 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.
+ */
+
+#include "rtc_base/numerics/moving_percentile_filter.h"
+
+#include <stdint.h>
+
+#include <algorithm>
+
+#include "test/gtest.h"
+
+namespace webrtc {
+
+// 25th percentile can be exactly found with a window of length 4.
+TEST(MovingPercentileFilter, Percentile25ReturnsMovingPercentile25WithWindow4) {
+  MovingPercentileFilter<int> perc25(0.25f, 4);
+  const int64_t kSamples[10] = {1, 2, 3, 4, 4, 4, 5, 6, 7, 8};
+  const int64_t kExpectedFilteredValues[10] = {1, 1, 1, 1, 2, 3, 4, 4, 4, 5};
+  for (size_t i = 0; i < 10; ++i) {
+    perc25.Insert(kSamples[i]);
+    EXPECT_EQ(kExpectedFilteredValues[i], perc25.GetFilteredValue());
+    EXPECT_EQ(std::min<size_t>(i + 1, 4), perc25.GetNumberOfSamplesStored());
+  }
+}
+
+// 90th percentile becomes the 67th percentile with a window of length 4.
+TEST(MovingPercentileFilter, Percentile90ReturnsMovingPercentile67WithWindow4) {
+  MovingPercentileFilter<int> perc67(0.67f, 4);
+  MovingPercentileFilter<int> perc90(0.9f, 4);
+  const int64_t kSamples[8] = {1, 10, 1, 9, 1, 10, 1, 8};
+  const int64_t kExpectedFilteredValues[9] = {1, 1, 1, 9, 9, 9, 9, 8};
+  for (size_t i = 0; i < 8; ++i) {
+    perc67.Insert(kSamples[i]);
+    perc90.Insert(kSamples[i]);
+    EXPECT_EQ(kExpectedFilteredValues[i], perc67.GetFilteredValue());
+    EXPECT_EQ(kExpectedFilteredValues[i], perc90.GetFilteredValue());
+  }
+}
+
+TEST(MovingMedianFilterTest, ProcessesNoSamples) {
+  MovingMedianFilter<int> filter(2);
+  EXPECT_EQ(0, filter.GetFilteredValue());
+  EXPECT_EQ(0u, filter.GetNumberOfSamplesStored());
+}
+
+TEST(MovingMedianFilterTest, ReturnsMovingMedianWindow5) {
+  MovingMedianFilter<int> filter(5);
+  const int64_t kSamples[5] = {1, 5, 2, 3, 4};
+  const int64_t kExpectedFilteredValues[5] = {1, 1, 2, 2, 3};
+  for (size_t i = 0; i < 5; ++i) {
+    filter.Insert(kSamples[i]);
+    EXPECT_EQ(kExpectedFilteredValues[i], filter.GetFilteredValue());
+    EXPECT_EQ(i + 1, filter.GetNumberOfSamplesStored());
+  }
+}
+
+TEST(MovingMedianFilterTest, ReturnsMovingMedianWindow3) {
+  MovingMedianFilter<int> filter(3);
+  const int64_t kSamples[5] = {1, 5, 2, 3, 4};
+  const int64_t kExpectedFilteredValues[5] = {1, 1, 2, 3, 3};
+  for (int i = 0; i < 5; ++i) {
+    filter.Insert(kSamples[i]);
+    EXPECT_EQ(kExpectedFilteredValues[i], filter.GetFilteredValue());
+    EXPECT_EQ(std::min<size_t>(i + 1, 3), filter.GetNumberOfSamplesStored());
+  }
+}
+
+TEST(MovingMedianFilterTest, ReturnsMovingMedianWindow1) {
+  MovingMedianFilter<int> filter(1);
+  const int64_t kSamples[5] = {1, 5, 2, 3, 4};
+  const int64_t kExpectedFilteredValues[5] = {1, 5, 2, 3, 4};
+  for (int i = 0; i < 5; ++i) {
+    filter.Insert(kSamples[i]);
+    EXPECT_EQ(kExpectedFilteredValues[i], filter.GetFilteredValue());
+    EXPECT_EQ(1u, filter.GetNumberOfSamplesStored());
+  }
+}
+
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/percentile_filter.h b/third_party/libwebrtc/rtc_base/numerics/percentile_filter.h
new file mode 100644
index 0000000000..2a18c1aa73
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/percentile_filter.h
@@ -0,0 +1,124 @@
+/*
+ *  Copyright (c) 2016 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_PERCENTILE_FILTER_H_
+#define RTC_BASE_NUMERICS_PERCENTILE_FILTER_H_
+
+#include <stdint.h>
+
+#include <iterator>
+#include <set>
+
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+
+// Class to efficiently get the percentile value from a group of observations.
+// The percentile is the value below which a given percentage of the
+// observations fall.
+template <typename T>
+class PercentileFilter {
+ public:
+  // Construct filter. `percentile` should be between 0 and 1.
+  explicit PercentileFilter(float percentile);
+
+  // Insert one observation. The complexity of this operation is logarithmic in
+  // the size of the container.
+  void Insert(const T& value);
+
+  // Remove one observation or return false if `value` doesn't exist in the
+  // container. The complexity of this operation is logarithmic in the size of
+  // the container.
+  bool Erase(const T& value);
+
+  // Get the percentile value. The complexity of this operation is constant.
+  T GetPercentileValue() const;
+
+  // Removes all the stored observations.
+  void Reset();
+
+ private:
+  // Update iterator and index to point at target percentile value.
+  void UpdatePercentileIterator();
+
+  const float percentile_;
+  std::multiset<T> set_;
+  // Maintain iterator and index of current target percentile value.
+  typename std::multiset<T>::iterator percentile_it_;
+  int64_t percentile_index_;
+};
+
+template <typename T>
+PercentileFilter<T>::PercentileFilter(float percentile)
+    : percentile_(percentile),
+      percentile_it_(set_.begin()),
+      percentile_index_(0) {
+  RTC_CHECK_GE(percentile, 0.0f);
+  RTC_CHECK_LE(percentile, 1.0f);
+}
+
+template <typename T>
+void PercentileFilter<T>::Insert(const T& value) {
+  // Insert element at the upper bound.
+  set_.insert(value);
+  if (set_.size() == 1u) {
+    // First element inserted - initialize percentile iterator and index.
+    percentile_it_ = set_.begin();
+    percentile_index_ = 0;
+  } else if (value < *percentile_it_) {
+    // If new element is before us, increment `percentile_index_`.
+    ++percentile_index_;
+  }
+  UpdatePercentileIterator();
+}
+
+template <typename T>
+bool PercentileFilter<T>::Erase(const T& value) {
+  typename std::multiset<T>::const_iterator it = set_.lower_bound(value);
+  // Ignore erase operation if the element is not present in the current set.
+  if (it == set_.end() || *it != value)
+    return false;
+  if (it == percentile_it_) {
+    // If same iterator, update to the following element. Index is not
+    // affected.
+    percentile_it_ = set_.erase(it);
+  } else {
+    set_.erase(it);
+    // If erased element was before us, decrement `percentile_index_`.
+    if (value <= *percentile_it_)
+      --percentile_index_;
+  }
+  UpdatePercentileIterator();
+  return true;
+}
+
+template <typename T>
+void PercentileFilter<T>::UpdatePercentileIterator() {
+  if (set_.empty())
+    return;
+  const int64_t index = static_cast<int64_t>(percentile_ * (set_.size() - 1));
+  std::advance(percentile_it_, index - percentile_index_);
+  percentile_index_ = index;
+}
+
+template <typename T>
+T PercentileFilter<T>::GetPercentileValue() const {
+  return set_.empty() ? 0 : *percentile_it_;
+}
+
+template <typename T>
+void PercentileFilter<T>::Reset() {
+  set_.clear();
+  percentile_it_ = set_.begin();
+  percentile_index_ = 0;
+}
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_PERCENTILE_FILTER_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/percentile_filter_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/percentile_filter_unittest.cc
new file mode 100644
index 0000000000..d6baa32001
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/percentile_filter_unittest.cc
@@ -0,0 +1,142 @@
+/*
+ *  Copyright 2016 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 "rtc_base/numerics/percentile_filter.h"
+
+#include <stdlib.h>
+
+#include <array>
+#include <climits>
+#include <cstdint>
+#include <random>
+
+#include "absl/algorithm/container.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+
+class PercentileFilterTest : public ::testing::TestWithParam<float> {
+ public:
+  PercentileFilterTest() : filter_(GetParam()) {
+    // Make sure the tests are deterministic by seeding with a constant.
+    srand(42);
+  }
+
+  PercentileFilterTest(const PercentileFilterTest&) = delete;
+  PercentileFilterTest& operator=(const PercentileFilterTest&) = delete;
+
+ protected:
+  PercentileFilter<int64_t> filter_;
+};
+
+INSTANTIATE_TEST_SUITE_P(PercentileFilterTests,
+                         PercentileFilterTest,
+                         ::testing::Values(0.0f, 0.1f, 0.5f, 0.9f, 1.0f));
+
+TEST(PercentileFilterTest, MinFilter) {
+  PercentileFilter<int64_t> filter(0.0f);
+  filter.Insert(4);
+  EXPECT_EQ(4, filter.GetPercentileValue());
+  filter.Insert(3);
+  EXPECT_EQ(3, filter.GetPercentileValue());
+}
+
+TEST(PercentileFilterTest, MaxFilter) {
+  PercentileFilter<int64_t> filter(1.0f);
+  filter.Insert(3);
+  EXPECT_EQ(3, filter.GetPercentileValue());
+  filter.Insert(4);
+  EXPECT_EQ(4, filter.GetPercentileValue());
+}
+
+TEST(PercentileFilterTest, MedianFilterDouble) {
+  PercentileFilter<double> filter(0.5f);
+  filter.Insert(2.71828);
+  filter.Insert(3.14159);
+  filter.Insert(1.41421);
+  EXPECT_EQ(2.71828, filter.GetPercentileValue());
+}
+
+TEST(PercentileFilterTest, MedianFilterInt) {
+  PercentileFilter<int> filter(0.5f);
+  filter.Insert(INT_MIN);
+  filter.Insert(1);
+  filter.Insert(2);
+  EXPECT_EQ(1, filter.GetPercentileValue());
+  filter.Insert(INT_MAX);
+  filter.Erase(INT_MIN);
+  EXPECT_EQ(2, filter.GetPercentileValue());
+}
+
+TEST(PercentileFilterTest, MedianFilterUnsigned) {
+  PercentileFilter<unsigned> filter(0.5f);
+  filter.Insert(UINT_MAX);
+  filter.Insert(2u);
+  filter.Insert(1u);
+  EXPECT_EQ(2u, filter.GetPercentileValue());
+  filter.Insert(0u);
+  filter.Erase(UINT_MAX);
+  EXPECT_EQ(1u, filter.GetPercentileValue());
+}
+
+TEST_P(PercentileFilterTest, EmptyFilter) {
+  EXPECT_EQ(0, filter_.GetPercentileValue());
+  filter_.Insert(3);
+  bool success = filter_.Erase(3);
+  EXPECT_TRUE(success);
+  EXPECT_EQ(0, filter_.GetPercentileValue());
+}
+
+TEST_P(PercentileFilterTest, EraseNonExistingElement) {
+  bool success = filter_.Erase(3);
+  EXPECT_FALSE(success);
+  EXPECT_EQ(0, filter_.GetPercentileValue());
+  filter_.Insert(4);
+  success = filter_.Erase(3);
+  EXPECT_FALSE(success);
+  EXPECT_EQ(4, filter_.GetPercentileValue());
+}
+
+TEST_P(PercentileFilterTest, DuplicateElements) {
+  filter_.Insert(3);
+  filter_.Insert(3);
+  filter_.Erase(3);
+  EXPECT_EQ(3, filter_.GetPercentileValue());
+}
+
+TEST_P(PercentileFilterTest, InsertAndEraseTenValuesInRandomOrder) {
+  std::array<int64_t, 10> zero_to_nine = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+  // The percentile value of the ten values above.
+  const int64_t expected_value = static_cast<int64_t>(GetParam() * 9);
+
+  // Insert two sets of `zero_to_nine` in random order.
+  for (int i = 0; i < 2; ++i) {
+    absl::c_shuffle(zero_to_nine, std::mt19937(std::random_device()()));
+    for (int64_t value : zero_to_nine)
+      filter_.Insert(value);
+    // After inserting a full set of `zero_to_nine`, the percentile should
+    // stay constant.
+    EXPECT_EQ(expected_value, filter_.GetPercentileValue());
+  }
+
+  // Insert and erase sets of `zero_to_nine` in random order a few times.
+  for (int i = 0; i < 3; ++i) {
+    absl::c_shuffle(zero_to_nine, std::mt19937(std::random_device()()));
+    for (int64_t value : zero_to_nine)
+      filter_.Erase(value);
+    EXPECT_EQ(expected_value, filter_.GetPercentileValue());
+    absl::c_shuffle(zero_to_nine, std::mt19937(std::random_device()()));
+    for (int64_t value : zero_to_nine)
+      filter_.Insert(value);
+    EXPECT_EQ(expected_value, filter_.GetPercentileValue());
+  }
+}
+
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/running_statistics.h b/third_party/libwebrtc/rtc_base/numerics/running_statistics.h
new file mode 100644
index 0000000000..bbcc7e2a73
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/running_statistics.h
@@ -0,0 +1,161 @@
+/*
+ *  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 API_NUMERICS_RUNNING_STATISTICS_H_
+#define API_NUMERICS_RUNNING_STATISTICS_H_
+
+#include <algorithm>
+#include <cmath>
+#include <limits>
+
+#include "absl/types/optional.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/math_utils.h"
+
+namespace webrtc {
+namespace webrtc_impl {
+
+// tl;dr: Robust and efficient online computation of statistics,
+//        using Welford's method for variance. [1]
+//
+// This should be your go-to class if you ever need to compute
+// min, max, mean, variance and standard deviation.
+// If you need to get percentiles, please use webrtc::SamplesStatsCounter.
+//
+// Please note RemoveSample() won't affect min and max.
+// If you want a full-fledged moving window over N last samples,
+// please use webrtc::RollingAccumulator.
+//
+// The measures return absl::nullopt if no samples were fed (Size() == 0),
+// otherwise the returned optional is guaranteed to contain a value.
+//
+// [1]
+// https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Welford's_online_algorithm
+
+// The type T is a scalar which must be convertible to double.
+// Rationale: we often need greater precision for measures
+//            than for the samples themselves.
+template <typename T>
+class RunningStatistics {
+ public:
+  // Update stats ////////////////////////////////////////////
+
+  // Add a value participating in the statistics in O(1) time.
+  void AddSample(T sample) {
+    max_ = std::max(max_, sample);
+    min_ = std::min(min_, sample);
+    ++size_;
+    // Welford's incremental update.
+    const double delta = sample - mean_;
+    mean_ += delta / size_;
+    const double delta2 = sample - mean_;
+    cumul_ += delta * delta2;
+  }
+
+  // Remove a previously added value in O(1) time.
+  // Nb: This doesn't affect min or max.
+  // Calling RemoveSample when Size()==0 is incorrect.
+  void RemoveSample(T sample) {
+    RTC_DCHECK_GT(Size(), 0);
+    // In production, just saturate at 0.
+    if (Size() == 0) {
+      return;
+    }
+    // Since samples order doesn't matter, this is the
+    // exact reciprocal of Welford's incremental update.
+    --size_;
+    const double delta = sample - mean_;
+    mean_ -= delta / size_;
+    const double delta2 = sample - mean_;
+    cumul_ -= delta * delta2;
+  }
+
+  // Merge other stats, as if samples were added one by one, but in O(1).
+  void MergeStatistics(const RunningStatistics<T>& other) {
+    if (other.size_ == 0) {
+      return;
+    }
+    max_ = std::max(max_, other.max_);
+    min_ = std::min(min_, other.min_);
+    const int64_t new_size = size_ + other.size_;
+    const double new_mean =
+        (mean_ * size_ + other.mean_ * other.size_) / new_size;
+    // Each cumulant must be corrected.
+    //   * from: sum((x_i - mean_)²)
+    //   * to:   sum((x_i - new_mean)²)
+    auto delta = [new_mean](const RunningStatistics<T>& stats) {
+      return stats.size_ * (new_mean * (new_mean - 2 * stats.mean_) +
+                            stats.mean_ * stats.mean_);
+    };
+    cumul_ = cumul_ + delta(*this) + other.cumul_ + delta(other);
+    mean_ = new_mean;
+    size_ = new_size;
+  }
+
+  // Get Measures ////////////////////////////////////////////
+
+  // Returns number of samples involved via AddSample() or MergeStatistics(),
+  // minus number of times RemoveSample() was called.
+  int64_t Size() const { return size_; }
+
+  // Returns minimum among all seen samples, in O(1) time.
+  // This isn't affected by RemoveSample().
+  absl::optional<T> GetMin() const {
+    if (size_ == 0) {
+      return absl::nullopt;
+    }
+    return min_;
+  }
+
+  // Returns maximum among all seen samples, in O(1) time.
+  // This isn't affected by RemoveSample().
+  absl::optional<T> GetMax() const {
+    if (size_ == 0) {
+      return absl::nullopt;
+    }
+    return max_;
+  }
+
+  // Returns mean in O(1) time.
+  absl::optional<double> GetMean() const {
+    if (size_ == 0) {
+      return absl::nullopt;
+    }
+    return mean_;
+  }
+
+  // Returns unbiased sample variance in O(1) time.
+  absl::optional<double> GetVariance() const {
+    if (size_ == 0) {
+      return absl::nullopt;
+    }
+    return cumul_ / size_;
+  }
+
+  // Returns unbiased standard deviation in O(1) time.
+  absl::optional<double> GetStandardDeviation() const {
+    if (size_ == 0) {
+      return absl::nullopt;
+    }
+    return std::sqrt(*GetVariance());
+  }
+
+ private:
+  int64_t size_ = 0;  // Samples seen.
+  T min_ = infinity_or_max<T>();
+  T max_ = minus_infinity_or_min<T>();
+  double mean_ = 0;
+  double cumul_ = 0;  // Variance * size_, sometimes noted m2.
+};
+
+}  // namespace webrtc_impl
+}  // namespace webrtc
+
+#endif  // API_NUMERICS_RUNNING_STATISTICS_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/running_statistics_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/running_statistics_unittest.cc
new file mode 100644
index 0000000000..d593f3fc5a
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/running_statistics_unittest.cc
@@ -0,0 +1,196 @@
+/*
+ *  Copyright (c) 2016 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 "rtc_base/numerics/running_statistics.h"
+
+#include <math.h>
+
+#include <random>
+#include <vector>
+
+#include "absl/algorithm/container.h"
+#include "test/gtest.h"
+
+// Tests were copied from samples_stats_counter_unittest.cc.
+
+namespace webrtc {
+namespace webrtc_impl {
+namespace {
+
+RunningStatistics<double> CreateStatsFilledWithIntsFrom1ToN(int n) {
+  std::vector<double> data;
+  for (int i = 1; i <= n; i++) {
+    data.push_back(i);
+  }
+  absl::c_shuffle(data, std::mt19937(std::random_device()()));
+
+  RunningStatistics<double> stats;
+  for (double v : data) {
+    stats.AddSample(v);
+  }
+  return stats;
+}
+
+// Add n samples drawn from uniform distribution in [a;b].
+RunningStatistics<double> CreateStatsFromUniformDistribution(int n,
+                                                             double a,
+                                                             double b) {
+  std::mt19937 gen{std::random_device()()};
+  std::uniform_real_distribution<> dis(a, b);
+
+  RunningStatistics<double> stats;
+  for (int i = 1; i <= n; i++) {
+    stats.AddSample(dis(gen));
+  }
+  return stats;
+}
+
+class RunningStatisticsTest : public ::testing::TestWithParam<int> {};
+
+constexpr int SIZE_FOR_MERGE = 5;
+
+TEST(RunningStatistics, FullSimpleTest) {
+  auto stats = CreateStatsFilledWithIntsFrom1ToN(100);
+
+  EXPECT_DOUBLE_EQ(*stats.GetMin(), 1.0);
+  EXPECT_DOUBLE_EQ(*stats.GetMax(), 100.0);
+  // EXPECT_DOUBLE_EQ is too strict (max 4 ULP) for this one.
+  ASSERT_NEAR(*stats.GetMean(), 50.5, 1e-10);
+}
+
+TEST(RunningStatistics, VarianceAndDeviation) {
+  RunningStatistics<int> stats;
+  stats.AddSample(2);
+  stats.AddSample(2);
+  stats.AddSample(-1);
+  stats.AddSample(5);
+
+  EXPECT_DOUBLE_EQ(*stats.GetMean(), 2.0);
+  EXPECT_DOUBLE_EQ(*stats.GetVariance(), 4.5);
+  EXPECT_DOUBLE_EQ(*stats.GetStandardDeviation(), sqrt(4.5));
+}
+
+TEST(RunningStatistics, RemoveSample) {
+  // We check that adding then removing sample is no-op,
+  // or so (due to loss of precision).
+  RunningStatistics<int> stats;
+  stats.AddSample(2);
+  stats.AddSample(2);
+  stats.AddSample(-1);
+  stats.AddSample(5);
+
+  constexpr int iterations = 1e5;
+  for (int i = 0; i < iterations; ++i) {
+    stats.AddSample(i);
+    stats.RemoveSample(i);
+
+    EXPECT_NEAR(*stats.GetMean(), 2.0, 1e-8);
+    EXPECT_NEAR(*stats.GetVariance(), 4.5, 1e-3);
+    EXPECT_NEAR(*stats.GetStandardDeviation(), sqrt(4.5), 1e-4);
+  }
+}
+
+TEST(RunningStatistics, RemoveSamplesSequence) {
+  // We check that adding then removing a sequence of samples is no-op,
+  // or so (due to loss of precision).
+  RunningStatistics<int> stats;
+  stats.AddSample(2);
+  stats.AddSample(2);
+  stats.AddSample(-1);
+  stats.AddSample(5);
+
+  constexpr int iterations = 1e4;
+  for (int i = 0; i < iterations; ++i) {
+    stats.AddSample(i);
+  }
+  for (int i = 0; i < iterations; ++i) {
+    stats.RemoveSample(i);
+  }
+
+  EXPECT_NEAR(*stats.GetMean(), 2.0, 1e-7);
+  EXPECT_NEAR(*stats.GetVariance(), 4.5, 1e-3);
+  EXPECT_NEAR(*stats.GetStandardDeviation(), sqrt(4.5), 1e-4);
+}
+
+TEST(RunningStatistics, VarianceFromUniformDistribution) {
+  // Check variance converge to 1/12 for [0;1) uniform distribution.
+  // Acts as a sanity check for NumericStabilityForVariance test.
+  auto stats = CreateStatsFromUniformDistribution(1e6, 0, 1);
+
+  EXPECT_NEAR(*stats.GetVariance(), 1. / 12, 1e-3);
+}
+
+TEST(RunningStatistics, NumericStabilityForVariance) {
+  // Same test as VarianceFromUniformDistribution,
+  // except the range is shifted to [1e9;1e9+1).
+  // Variance should also converge to 1/12.
+  // NB: Although we lose precision for the samples themselves, the fractional
+  //     part still enjoys 22 bits of mantissa and errors should even out,
+  //     so that couldn't explain a mismatch.
+  auto stats = CreateStatsFromUniformDistribution(1e6, 1e9, 1e9 + 1);
+
+  EXPECT_NEAR(*stats.GetVariance(), 1. / 12, 1e-3);
+}
+
+TEST(RunningStatistics, MinRemainsUnchangedAfterRemove) {
+  // We don't want to recompute min (that's RollingAccumulator's role),
+  // check we get the overall min.
+  RunningStatistics<int> stats;
+  stats.AddSample(1);
+  stats.AddSample(2);
+  stats.RemoveSample(1);
+  EXPECT_EQ(stats.GetMin(), 1);
+}
+
+TEST(RunningStatistics, MaxRemainsUnchangedAfterRemove) {
+  // We don't want to recompute max (that's RollingAccumulator's role),
+  // check we get the overall max.
+  RunningStatistics<int> stats;
+  stats.AddSample(1);
+  stats.AddSample(2);
+  stats.RemoveSample(2);
+  EXPECT_EQ(stats.GetMax(), 2);
+}
+
+TEST_P(RunningStatisticsTest, MergeStatistics) {
+  int data[SIZE_FOR_MERGE] = {2, 2, -1, 5, 10};
+  // Split the data in different partitions.
+  // We have 6 distinct tests:
+  //   * Empty merged with full sequence.
+  //   * 1 sample merged with 4 last.
+  //   * 2 samples merged with 3 last.
+  //   [...]
+  //   * Full merged with empty sequence.
+  // All must lead to the same result.
+  // I miss QuickCheck so much.
+  RunningStatistics<int> stats0, stats1;
+  for (int i = 0; i < GetParam(); ++i) {
+    stats0.AddSample(data[i]);
+  }
+  for (int i = GetParam(); i < SIZE_FOR_MERGE; ++i) {
+    stats1.AddSample(data[i]);
+  }
+  stats0.MergeStatistics(stats1);
+
+  EXPECT_EQ(stats0.Size(), SIZE_FOR_MERGE);
+  EXPECT_DOUBLE_EQ(*stats0.GetMin(), -1);
+  EXPECT_DOUBLE_EQ(*stats0.GetMax(), 10);
+  EXPECT_DOUBLE_EQ(*stats0.GetMean(), 3.6);
+  EXPECT_DOUBLE_EQ(*stats0.GetVariance(), 13.84);
+  EXPECT_DOUBLE_EQ(*stats0.GetStandardDeviation(), sqrt(13.84));
+}
+
+INSTANTIATE_TEST_SUITE_P(RunningStatisticsTests,
+                         RunningStatisticsTest,
+                         ::testing::Range(0, SIZE_FOR_MERGE + 1));
+
+}  // namespace
+}  // namespace webrtc_impl
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/safe_compare.h b/third_party/libwebrtc/rtc_base/numerics/safe_compare.h
new file mode 100644
index 0000000000..85f0a30e83
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/safe_compare.h
@@ -0,0 +1,176 @@
+/*
+ *  Copyright 2016 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.
+ */
+
+// This file defines six constexpr functions:
+//
+//   rtc::SafeEq  // ==
+//   rtc::SafeNe  // !=
+//   rtc::SafeLt  // <
+//   rtc::SafeLe  // <=
+//   rtc::SafeGt  // >
+//   rtc::SafeGe  // >=
+//
+// They each accept two arguments of arbitrary types, and in almost all cases,
+// they simply call the appropriate comparison operator. However, if both
+// arguments are integers, they don't compare them using C++'s quirky rules,
+// but instead adhere to the true mathematical definitions. It is as if the
+// arguments were first converted to infinite-range signed integers, and then
+// compared, although of course nothing expensive like that actually takes
+// place. In practice, for signed/signed and unsigned/unsigned comparisons and
+// some mixed-signed comparisons with a compile-time constant, the overhead is
+// zero; in the remaining cases, it is just a few machine instructions (no
+// branches).
+
+#ifndef RTC_BASE_NUMERICS_SAFE_COMPARE_H_
+#define RTC_BASE_NUMERICS_SAFE_COMPARE_H_
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <type_traits>
+#include <utility>
+
+#include "rtc_base/type_traits.h"
+
+namespace rtc {
+
+namespace safe_cmp_impl {
+
+template <size_t N>
+struct LargerIntImpl : std::false_type {};
+template <>
+struct LargerIntImpl<sizeof(int8_t)> : std::true_type {
+  using type = int16_t;
+};
+template <>
+struct LargerIntImpl<sizeof(int16_t)> : std::true_type {
+  using type = int32_t;
+};
+template <>
+struct LargerIntImpl<sizeof(int32_t)> : std::true_type {
+  using type = int64_t;
+};
+
+// LargerInt<T1, T2>::value is true iff there's a signed type that's larger
+// than T1 (and no larger than the larger of T2 and int*, for performance
+// reasons); and if there is such a type, LargerInt<T1, T2>::type is an alias
+// for it.
+template <typename T1, typename T2>
+struct LargerInt
+    : LargerIntImpl<sizeof(T1) < sizeof(T2) || sizeof(T1) < sizeof(int*)
+                        ? sizeof(T1)
+                        : 0> {};
+
+template <typename T>
+constexpr typename std::make_unsigned<T>::type MakeUnsigned(T a) {
+  return static_cast<typename std::make_unsigned<T>::type>(a);
+}
+
+// Overload for when both T1 and T2 have the same signedness.
+template <typename Op,
+          typename T1,
+          typename T2,
+          typename std::enable_if<std::is_signed<T1>::value ==
+                                  std::is_signed<T2>::value>::type* = nullptr>
+constexpr bool Cmp(T1 a, T2 b) {
+  return Op::Op(a, b);
+}
+
+// Overload for signed - unsigned comparison that can be promoted to a bigger
+// signed type.
+template <typename Op,
+          typename T1,
+          typename T2,
+          typename std::enable_if<std::is_signed<T1>::value &&
+                                  std::is_unsigned<T2>::value &&
+                                  LargerInt<T2, T1>::value>::type* = nullptr>
+constexpr bool Cmp(T1 a, T2 b) {
+  return Op::Op(a, static_cast<typename LargerInt<T2, T1>::type>(b));
+}
+
+// Overload for unsigned - signed comparison that can be promoted to a bigger
+// signed type.
+template <typename Op,
+          typename T1,
+          typename T2,
+          typename std::enable_if<std::is_unsigned<T1>::value &&
+                                  std::is_signed<T2>::value &&
+                                  LargerInt<T1, T2>::value>::type* = nullptr>
+constexpr bool Cmp(T1 a, T2 b) {
+  return Op::Op(static_cast<typename LargerInt<T1, T2>::type>(a), b);
+}
+
+// Overload for signed - unsigned comparison that can't be promoted to a bigger
+// signed type.
+template <typename Op,
+          typename T1,
+          typename T2,
+          typename std::enable_if<std::is_signed<T1>::value &&
+                                  std::is_unsigned<T2>::value &&
+                                  !LargerInt<T2, T1>::value>::type* = nullptr>
+constexpr bool Cmp(T1 a, T2 b) {
+  return a < 0 ? Op::Op(-1, 0) : Op::Op(safe_cmp_impl::MakeUnsigned(a), b);
+}
+
+// Overload for unsigned - signed comparison that can't be promoted to a bigger
+// signed type.
+template <typename Op,
+          typename T1,
+          typename T2,
+          typename std::enable_if<std::is_unsigned<T1>::value &&
+                                  std::is_signed<T2>::value &&
+                                  !LargerInt<T1, T2>::value>::type* = nullptr>
+constexpr bool Cmp(T1 a, T2 b) {
+  return b < 0 ? Op::Op(0, -1) : Op::Op(a, safe_cmp_impl::MakeUnsigned(b));
+}
+
+#define RTC_SAFECMP_MAKE_OP(name, op)      \
+  struct name {                            \
+    template <typename T1, typename T2>    \
+    static constexpr bool Op(T1 a, T2 b) { \
+      return a op b;                       \
+    }                                      \
+  };
+RTC_SAFECMP_MAKE_OP(EqOp, ==)
+RTC_SAFECMP_MAKE_OP(NeOp, !=)
+RTC_SAFECMP_MAKE_OP(LtOp, <)
+RTC_SAFECMP_MAKE_OP(LeOp, <=)
+RTC_SAFECMP_MAKE_OP(GtOp, >)
+RTC_SAFECMP_MAKE_OP(GeOp, >=)
+#undef RTC_SAFECMP_MAKE_OP
+
+}  // namespace safe_cmp_impl
+
+#define RTC_SAFECMP_MAKE_FUN(name)                                            \
+  template <typename T1, typename T2>                                         \
+  constexpr                                                                   \
+      typename std::enable_if<IsIntlike<T1>::value && IsIntlike<T2>::value,   \
+                              bool>::type Safe##name(T1 a, T2 b) {            \
+    /* Unary plus here turns enums into real integral types. */               \
+    return safe_cmp_impl::Cmp<safe_cmp_impl::name##Op>(+a, +b);               \
+  }                                                                           \
+  template <typename T1, typename T2>                                         \
+  constexpr                                                                   \
+      typename std::enable_if<!IsIntlike<T1>::value || !IsIntlike<T2>::value, \
+                              bool>::type Safe##name(const T1& a,             \
+                                                     const T2& b) {           \
+    return safe_cmp_impl::name##Op::Op(a, b);                                 \
+  }
+RTC_SAFECMP_MAKE_FUN(Eq)
+RTC_SAFECMP_MAKE_FUN(Ne)
+RTC_SAFECMP_MAKE_FUN(Lt)
+RTC_SAFECMP_MAKE_FUN(Le)
+RTC_SAFECMP_MAKE_FUN(Gt)
+RTC_SAFECMP_MAKE_FUN(Ge)
+#undef RTC_SAFECMP_MAKE_FUN
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_NUMERICS_SAFE_COMPARE_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/safe_compare_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/safe_compare_unittest.cc
new file mode 100644
index 0000000000..92bde686ba
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/safe_compare_unittest.cc
@@ -0,0 +1,395 @@
+/*
+ *  Copyright 2016 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 "rtc_base/numerics/safe_compare.h"
+
+#include <limits>
+
+#include "test/gtest.h"
+
+namespace rtc {
+
+namespace {
+
+constexpr std::uintmax_t umax = std::numeric_limits<std::uintmax_t>::max();
+constexpr std::intmax_t imin = std::numeric_limits<std::intmax_t>::min();
+constexpr std::intmax_t m1 = -1;
+
+// m1 and umax have the same representation because we use 2's complement
+// arithmetic, so naive casting will confuse them.
+static_assert(static_cast<std::uintmax_t>(m1) == umax, "");
+static_assert(m1 == static_cast<std::intmax_t>(umax), "");
+
+static const std::pair<int, int> p1(1, 1);
+static const std::pair<int, int> p2(1, 2);
+
+}  // namespace
+
+// clang-format off
+
+// These functions aren't used in the tests, but it's useful to look at the
+// compiler output for them, and verify that (1) the same-signedness *Safe
+// functions result in exactly the same code as their *Ref counterparts, and
+// that (2) the mixed-signedness *Safe functions have just a few extra
+// arithmetic and logic instructions (but no extra control flow instructions).
+bool TestLessThanRef(      int a,      int b) { return a < b; }
+bool TestLessThanRef( unsigned a, unsigned b) { return a < b; }
+bool TestLessThanSafe(     int a,      int b) { return SafeLt(a, b); }
+bool TestLessThanSafe(unsigned a, unsigned b) { return SafeLt(a, b); }
+bool TestLessThanSafe(unsigned a,      int b) { return SafeLt(a, b); }
+bool TestLessThanSafe(     int a, unsigned b) { return SafeLt(a, b); }
+
+// For these, we expect the *Ref and *Safe functions to result in identical
+// code, except for the ones that compare a signed variable with an unsigned
+// constant; in that case, the *Ref function does an unsigned comparison (fast
+// but incorrect) and the *Safe function spends a few extra instructions on
+// doing it right.
+bool TestLessThan17Ref(       int a) { return a < 17; }
+bool TestLessThan17Ref(  unsigned a) { return a < 17; }
+bool TestLessThan17uRef(      int a) { return static_cast<unsigned>(a) < 17u; }
+bool TestLessThan17uRef( unsigned a) { return a < 17u; }
+bool TestLessThan17Safe(      int a) { return SafeLt(a, 17); }
+bool TestLessThan17Safe( unsigned a) { return SafeLt(a, 17); }
+bool TestLessThan17uSafe(     int a) { return SafeLt(a, 17u); }
+bool TestLessThan17uSafe(unsigned a) { return SafeLt(a, 17u); }
+
+// Cases where we can't convert to a larger signed type.
+bool TestLessThanMax( intmax_t a, uintmax_t b) { return SafeLt(a, b); }
+bool TestLessThanMax(uintmax_t a,  intmax_t b) { return SafeLt(a, b); }
+bool TestLessThanMax17u( intmax_t a) { return SafeLt(a, uintmax_t{17}); }
+bool TestLessThanMax17( uintmax_t a) { return SafeLt(a,  intmax_t{17}); }
+
+// Cases where the compiler should be able to compute the result at compile
+// time.
+bool TestLessThanConst1() { return SafeLt(  -1,    1); }
+bool TestLessThanConst2() { return SafeLt(  m1, umax); }
+bool TestLessThanConst3() { return SafeLt(umax, imin); }
+bool TestLessThanConst4(unsigned a) { return SafeLt( a, -1); }
+bool TestLessThanConst5(unsigned a) { return SafeLt(-1,  a); }
+bool TestLessThanConst6(unsigned a) { return SafeLt( a,  a); }
+
+// clang-format on
+
+TEST(SafeCmpTest, Eq) {
+  static_assert(!SafeEq(-1, 2), "");
+  static_assert(!SafeEq(-1, 2u), "");
+  static_assert(!SafeEq(2, -1), "");
+  static_assert(!SafeEq(2u, -1), "");
+
+  static_assert(!SafeEq(1, 2), "");
+  static_assert(!SafeEq(1, 2u), "");
+  static_assert(!SafeEq(1u, 2), "");
+  static_assert(!SafeEq(1u, 2u), "");
+  static_assert(!SafeEq(2, 1), "");
+  static_assert(!SafeEq(2, 1u), "");
+  static_assert(!SafeEq(2u, 1), "");
+  static_assert(!SafeEq(2u, 1u), "");
+
+  static_assert(SafeEq(2, 2), "");
+  static_assert(SafeEq(2, 2u), "");
+  static_assert(SafeEq(2u, 2), "");
+  static_assert(SafeEq(2u, 2u), "");
+
+  static_assert(SafeEq(imin, imin), "");
+  static_assert(!SafeEq(imin, umax), "");
+  static_assert(!SafeEq(umax, imin), "");
+  static_assert(SafeEq(umax, umax), "");
+
+  static_assert(SafeEq(m1, m1), "");
+  static_assert(!SafeEq(m1, umax), "");
+  static_assert(!SafeEq(umax, m1), "");
+  static_assert(SafeEq(umax, umax), "");
+
+  static_assert(!SafeEq(1, 2), "");
+  static_assert(!SafeEq(1, 2.0), "");
+  static_assert(!SafeEq(1.0, 2), "");
+  static_assert(!SafeEq(1.0, 2.0), "");
+  static_assert(!SafeEq(2, 1), "");
+  static_assert(!SafeEq(2, 1.0), "");
+  static_assert(!SafeEq(2.0, 1), "");
+  static_assert(!SafeEq(2.0, 1.0), "");
+
+  static_assert(SafeEq(2, 2), "");
+  static_assert(SafeEq(2, 2.0), "");
+  static_assert(SafeEq(2.0, 2), "");
+  static_assert(SafeEq(2.0, 2.0), "");
+
+  EXPECT_TRUE(SafeEq(p1, p1));
+  EXPECT_FALSE(SafeEq(p1, p2));
+  EXPECT_FALSE(SafeEq(p2, p1));
+  EXPECT_TRUE(SafeEq(p2, p2));
+}
+
+TEST(SafeCmpTest, Ne) {
+  static_assert(SafeNe(-1, 2), "");
+  static_assert(SafeNe(-1, 2u), "");
+  static_assert(SafeNe(2, -1), "");
+  static_assert(SafeNe(2u, -1), "");
+
+  static_assert(SafeNe(1, 2), "");
+  static_assert(SafeNe(1, 2u), "");
+  static_assert(SafeNe(1u, 2), "");
+  static_assert(SafeNe(1u, 2u), "");
+  static_assert(SafeNe(2, 1), "");
+  static_assert(SafeNe(2, 1u), "");
+  static_assert(SafeNe(2u, 1), "");
+  static_assert(SafeNe(2u, 1u), "");
+
+  static_assert(!SafeNe(2, 2), "");
+  static_assert(!SafeNe(2, 2u), "");
+  static_assert(!SafeNe(2u, 2), "");
+  static_assert(!SafeNe(2u, 2u), "");
+
+  static_assert(!SafeNe(imin, imin), "");
+  static_assert(SafeNe(imin, umax), "");
+  static_assert(SafeNe(umax, imin), "");
+  static_assert(!SafeNe(umax, umax), "");
+
+  static_assert(!SafeNe(m1, m1), "");
+  static_assert(SafeNe(m1, umax), "");
+  static_assert(SafeNe(umax, m1), "");
+  static_assert(!SafeNe(umax, umax), "");
+
+  static_assert(SafeNe(1, 2), "");
+  static_assert(SafeNe(1, 2.0), "");
+  static_assert(SafeNe(1.0, 2), "");
+  static_assert(SafeNe(1.0, 2.0), "");
+  static_assert(SafeNe(2, 1), "");
+  static_assert(SafeNe(2, 1.0), "");
+  static_assert(SafeNe(2.0, 1), "");
+  static_assert(SafeNe(2.0, 1.0), "");
+
+  static_assert(!SafeNe(2, 2), "");
+  static_assert(!SafeNe(2, 2.0), "");
+  static_assert(!SafeNe(2.0, 2), "");
+  static_assert(!SafeNe(2.0, 2.0), "");
+
+  EXPECT_FALSE(SafeNe(p1, p1));
+  EXPECT_TRUE(SafeNe(p1, p2));
+  EXPECT_TRUE(SafeNe(p2, p1));
+  EXPECT_FALSE(SafeNe(p2, p2));
+}
+
+TEST(SafeCmpTest, Lt) {
+  static_assert(SafeLt(-1, 2), "");
+  static_assert(SafeLt(-1, 2u), "");
+  static_assert(!SafeLt(2, -1), "");
+  static_assert(!SafeLt(2u, -1), "");
+
+  static_assert(SafeLt(1, 2), "");
+  static_assert(SafeLt(1, 2u), "");
+  static_assert(SafeLt(1u, 2), "");
+  static_assert(SafeLt(1u, 2u), "");
+  static_assert(!SafeLt(2, 1), "");
+  static_assert(!SafeLt(2, 1u), "");
+  static_assert(!SafeLt(2u, 1), "");
+  static_assert(!SafeLt(2u, 1u), "");
+
+  static_assert(!SafeLt(2, 2), "");
+  static_assert(!SafeLt(2, 2u), "");
+  static_assert(!SafeLt(2u, 2), "");
+  static_assert(!SafeLt(2u, 2u), "");
+
+  static_assert(!SafeLt(imin, imin), "");
+  static_assert(SafeLt(imin, umax), "");
+  static_assert(!SafeLt(umax, imin), "");
+  static_assert(!SafeLt(umax, umax), "");
+
+  static_assert(!SafeLt(m1, m1), "");
+  static_assert(SafeLt(m1, umax), "");
+  static_assert(!SafeLt(umax, m1), "");
+  static_assert(!SafeLt(umax, umax), "");
+
+  static_assert(SafeLt(1, 2), "");
+  static_assert(SafeLt(1, 2.0), "");
+  static_assert(SafeLt(1.0, 2), "");
+  static_assert(SafeLt(1.0, 2.0), "");
+  static_assert(!SafeLt(2, 1), "");
+  static_assert(!SafeLt(2, 1.0), "");
+  static_assert(!SafeLt(2.0, 1), "");
+  static_assert(!SafeLt(2.0, 1.0), "");
+
+  static_assert(!SafeLt(2, 2), "");
+  static_assert(!SafeLt(2, 2.0), "");
+  static_assert(!SafeLt(2.0, 2), "");
+  static_assert(!SafeLt(2.0, 2.0), "");
+
+  EXPECT_FALSE(SafeLt(p1, p1));
+  EXPECT_TRUE(SafeLt(p1, p2));
+  EXPECT_FALSE(SafeLt(p2, p1));
+  EXPECT_FALSE(SafeLt(p2, p2));
+}
+
+TEST(SafeCmpTest, Le) {
+  static_assert(SafeLe(-1, 2), "");
+  static_assert(SafeLe(-1, 2u), "");
+  static_assert(!SafeLe(2, -1), "");
+  static_assert(!SafeLe(2u, -1), "");
+
+  static_assert(SafeLe(1, 2), "");
+  static_assert(SafeLe(1, 2u), "");
+  static_assert(SafeLe(1u, 2), "");
+  static_assert(SafeLe(1u, 2u), "");
+  static_assert(!SafeLe(2, 1), "");
+  static_assert(!SafeLe(2, 1u), "");
+  static_assert(!SafeLe(2u, 1), "");
+  static_assert(!SafeLe(2u, 1u), "");
+
+  static_assert(SafeLe(2, 2), "");
+  static_assert(SafeLe(2, 2u), "");
+  static_assert(SafeLe(2u, 2), "");
+  static_assert(SafeLe(2u, 2u), "");
+
+  static_assert(SafeLe(imin, imin), "");
+  static_assert(SafeLe(imin, umax), "");
+  static_assert(!SafeLe(umax, imin), "");
+  static_assert(SafeLe(umax, umax), "");
+
+  static_assert(SafeLe(m1, m1), "");
+  static_assert(SafeLe(m1, umax), "");
+  static_assert(!SafeLe(umax, m1), "");
+  static_assert(SafeLe(umax, umax), "");
+
+  static_assert(SafeLe(1, 2), "");
+  static_assert(SafeLe(1, 2.0), "");
+  static_assert(SafeLe(1.0, 2), "");
+  static_assert(SafeLe(1.0, 2.0), "");
+  static_assert(!SafeLe(2, 1), "");
+  static_assert(!SafeLe(2, 1.0), "");
+  static_assert(!SafeLe(2.0, 1), "");
+  static_assert(!SafeLe(2.0, 1.0), "");
+
+  static_assert(SafeLe(2, 2), "");
+  static_assert(SafeLe(2, 2.0), "");
+  static_assert(SafeLe(2.0, 2), "");
+  static_assert(SafeLe(2.0, 2.0), "");
+
+  EXPECT_TRUE(SafeLe(p1, p1));
+  EXPECT_TRUE(SafeLe(p1, p2));
+  EXPECT_FALSE(SafeLe(p2, p1));
+  EXPECT_TRUE(SafeLe(p2, p2));
+}
+
+TEST(SafeCmpTest, Gt) {
+  static_assert(!SafeGt(-1, 2), "");
+  static_assert(!SafeGt(-1, 2u), "");
+  static_assert(SafeGt(2, -1), "");
+  static_assert(SafeGt(2u, -1), "");
+
+  static_assert(!SafeGt(1, 2), "");
+  static_assert(!SafeGt(1, 2u), "");
+  static_assert(!SafeGt(1u, 2), "");
+  static_assert(!SafeGt(1u, 2u), "");
+  static_assert(SafeGt(2, 1), "");
+  static_assert(SafeGt(2, 1u), "");
+  static_assert(SafeGt(2u, 1), "");
+  static_assert(SafeGt(2u, 1u), "");
+
+  static_assert(!SafeGt(2, 2), "");
+  static_assert(!SafeGt(2, 2u), "");
+  static_assert(!SafeGt(2u, 2), "");
+  static_assert(!SafeGt(2u, 2u), "");
+
+  static_assert(!SafeGt(imin, imin), "");
+  static_assert(!SafeGt(imin, umax), "");
+  static_assert(SafeGt(umax, imin), "");
+  static_assert(!SafeGt(umax, umax), "");
+
+  static_assert(!SafeGt(m1, m1), "");
+  static_assert(!SafeGt(m1, umax), "");
+  static_assert(SafeGt(umax, m1), "");
+  static_assert(!SafeGt(umax, umax), "");
+
+  static_assert(!SafeGt(1, 2), "");
+  static_assert(!SafeGt(1, 2.0), "");
+  static_assert(!SafeGt(1.0, 2), "");
+  static_assert(!SafeGt(1.0, 2.0), "");
+  static_assert(SafeGt(2, 1), "");
+  static_assert(SafeGt(2, 1.0), "");
+  static_assert(SafeGt(2.0, 1), "");
+  static_assert(SafeGt(2.0, 1.0), "");
+
+  static_assert(!SafeGt(2, 2), "");
+  static_assert(!SafeGt(2, 2.0), "");
+  static_assert(!SafeGt(2.0, 2), "");
+  static_assert(!SafeGt(2.0, 2.0), "");
+
+  EXPECT_FALSE(SafeGt(p1, p1));
+  EXPECT_FALSE(SafeGt(p1, p2));
+  EXPECT_TRUE(SafeGt(p2, p1));
+  EXPECT_FALSE(SafeGt(p2, p2));
+}
+
+TEST(SafeCmpTest, Ge) {
+  static_assert(!SafeGe(-1, 2), "");
+  static_assert(!SafeGe(-1, 2u), "");
+  static_assert(SafeGe(2, -1), "");
+  static_assert(SafeGe(2u, -1), "");
+
+  static_assert(!SafeGe(1, 2), "");
+  static_assert(!SafeGe(1, 2u), "");
+  static_assert(!SafeGe(1u, 2), "");
+  static_assert(!SafeGe(1u, 2u), "");
+  static_assert(SafeGe(2, 1), "");
+  static_assert(SafeGe(2, 1u), "");
+  static_assert(SafeGe(2u, 1), "");
+  static_assert(SafeGe(2u, 1u), "");
+
+  static_assert(SafeGe(2, 2), "");
+  static_assert(SafeGe(2, 2u), "");
+  static_assert(SafeGe(2u, 2), "");
+  static_assert(SafeGe(2u, 2u), "");
+
+  static_assert(SafeGe(imin, imin), "");
+  static_assert(!SafeGe(imin, umax), "");
+  static_assert(SafeGe(umax, imin), "");
+  static_assert(SafeGe(umax, umax), "");
+
+  static_assert(SafeGe(m1, m1), "");
+  static_assert(!SafeGe(m1, umax), "");
+  static_assert(SafeGe(umax, m1), "");
+  static_assert(SafeGe(umax, umax), "");
+
+  static_assert(!SafeGe(1, 2), "");
+  static_assert(!SafeGe(1, 2.0), "");
+  static_assert(!SafeGe(1.0, 2), "");
+  static_assert(!SafeGe(1.0, 2.0), "");
+  static_assert(SafeGe(2, 1), "");
+  static_assert(SafeGe(2, 1.0), "");
+  static_assert(SafeGe(2.0, 1), "");
+  static_assert(SafeGe(2.0, 1.0), "");
+
+  static_assert(SafeGe(2, 2), "");
+  static_assert(SafeGe(2, 2.0), "");
+  static_assert(SafeGe(2.0, 2), "");
+  static_assert(SafeGe(2.0, 2.0), "");
+
+  EXPECT_TRUE(SafeGe(p1, p1));
+  EXPECT_FALSE(SafeGe(p1, p2));
+  EXPECT_TRUE(SafeGe(p2, p1));
+  EXPECT_TRUE(SafeGe(p2, p2));
+}
+
+TEST(SafeCmpTest, Enum) {
+  enum E1 { e1 = 13 };
+  enum { e2 = 13 };
+  enum E3 : unsigned { e3 = 13 };
+  enum : unsigned { e4 = 13 };
+  static_assert(SafeEq(13, e1), "");
+  static_assert(SafeEq(13u, e1), "");
+  static_assert(SafeEq(13, e2), "");
+  static_assert(SafeEq(13u, e2), "");
+  static_assert(SafeEq(13, e3), "");
+  static_assert(SafeEq(13u, e3), "");
+  static_assert(SafeEq(13, e4), "");
+  static_assert(SafeEq(13u, e4), "");
+}
+
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/safe_conversions.h b/third_party/libwebrtc/rtc_base/numerics/safe_conversions.h
new file mode 100644
index 0000000000..e00219cbd7
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/safe_conversions.h
@@ -0,0 +1,74 @@
+/*
+ *  Copyright 2014 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.
+ */
+
+// Borrowed from Chromium's src/base/numerics/safe_conversions.h.
+
+#ifndef RTC_BASE_NUMERICS_SAFE_CONVERSIONS_H_
+#define RTC_BASE_NUMERICS_SAFE_CONVERSIONS_H_
+
+#include <limits>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/safe_conversions_impl.h"
+
+namespace rtc {
+
+// Convenience function that returns true if the supplied value is in range
+// for the destination type.
+template <typename Dst, typename Src>
+inline constexpr bool IsValueInRangeForNumericType(Src value) {
+  return internal::RangeCheck<Dst>(value) == internal::TYPE_VALID;
+}
+
+// checked_cast<> and dchecked_cast<> are analogous to static_cast<> for
+// numeric types, except that they [D]CHECK that the specified numeric
+// conversion will not overflow or underflow. NaN source will always trigger
+// the [D]CHECK.
+template <typename Dst, typename Src>
+inline constexpr Dst checked_cast(Src value) {
+  RTC_CHECK(IsValueInRangeForNumericType<Dst>(value));
+  return static_cast<Dst>(value);
+}
+template <typename Dst, typename Src>
+inline constexpr Dst dchecked_cast(Src value) {
+  RTC_DCHECK(IsValueInRangeForNumericType<Dst>(value));
+  return static_cast<Dst>(value);
+}
+
+// saturated_cast<> is analogous to static_cast<> for numeric types, except
+// that the specified numeric conversion will saturate rather than overflow or
+// underflow. NaN assignment to an integral will trigger a RTC_CHECK condition.
+template <typename Dst, typename Src>
+inline constexpr Dst saturated_cast(Src value) {
+  // Optimization for floating point values, which already saturate.
+  if (std::numeric_limits<Dst>::is_iec559)
+    return static_cast<Dst>(value);
+
+  switch (internal::RangeCheck<Dst>(value)) {
+    case internal::TYPE_VALID:
+      return static_cast<Dst>(value);
+
+    case internal::TYPE_UNDERFLOW:
+      return std::numeric_limits<Dst>::min();
+
+    case internal::TYPE_OVERFLOW:
+      return std::numeric_limits<Dst>::max();
+
+    // Should fail only on attempting to assign NaN to a saturated integer.
+    case internal::TYPE_INVALID:
+      RTC_CHECK_NOTREACHED();
+  }
+
+  RTC_CHECK_NOTREACHED();
+}
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_NUMERICS_SAFE_CONVERSIONS_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/safe_conversions_impl.h b/third_party/libwebrtc/rtc_base/numerics/safe_conversions_impl.h
new file mode 100644
index 0000000000..e924ce3256
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/safe_conversions_impl.h
@@ -0,0 +1,177 @@
+/*
+ *  Copyright 2014 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.
+ */
+
+// Borrowed from Chromium's src/base/numerics/safe_conversions_impl.h.
+
+#ifndef RTC_BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
+#define RTC_BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
+
+#include <limits>
+
+namespace rtc {
+namespace internal {
+
+enum DstSign { DST_UNSIGNED, DST_SIGNED };
+
+enum SrcSign { SRC_UNSIGNED, SRC_SIGNED };
+
+enum DstRange { OVERLAPS_RANGE, CONTAINS_RANGE };
+
+// Helper templates to statically determine if our destination type can contain
+// all values represented by the source type.
+
+template <typename Dst,
+          typename Src,
+          DstSign IsDstSigned =
+              std::numeric_limits<Dst>::is_signed ? DST_SIGNED : DST_UNSIGNED,
+          SrcSign IsSrcSigned =
+              std::numeric_limits<Src>::is_signed ? SRC_SIGNED : SRC_UNSIGNED>
+struct StaticRangeCheck {};
+
+template <typename Dst, typename Src>
+struct StaticRangeCheck<Dst, Src, DST_SIGNED, SRC_SIGNED> {
+  typedef std::numeric_limits<Dst> DstLimits;
+  typedef std::numeric_limits<Src> SrcLimits;
+  // Compare based on max_exponent, which we must compute for integrals.
+  static const size_t kDstMaxExponent =
+      DstLimits::is_iec559 ? DstLimits::max_exponent : (sizeof(Dst) * 8 - 1);
+  static const size_t kSrcMaxExponent =
+      SrcLimits::is_iec559 ? SrcLimits::max_exponent : (sizeof(Src) * 8 - 1);
+  static const DstRange value =
+      kDstMaxExponent >= kSrcMaxExponent ? CONTAINS_RANGE : OVERLAPS_RANGE;
+};
+
+template <typename Dst, typename Src>
+struct StaticRangeCheck<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED> {
+  static const DstRange value =
+      sizeof(Dst) >= sizeof(Src) ? CONTAINS_RANGE : OVERLAPS_RANGE;
+};
+
+template <typename Dst, typename Src>
+struct StaticRangeCheck<Dst, Src, DST_SIGNED, SRC_UNSIGNED> {
+  typedef std::numeric_limits<Dst> DstLimits;
+  typedef std::numeric_limits<Src> SrcLimits;
+  // Compare based on max_exponent, which we must compute for integrals.
+  static const size_t kDstMaxExponent =
+      DstLimits::is_iec559 ? DstLimits::max_exponent : (sizeof(Dst) * 8 - 1);
+  static const size_t kSrcMaxExponent = sizeof(Src) * 8;
+  static const DstRange value =
+      kDstMaxExponent >= kSrcMaxExponent ? CONTAINS_RANGE : OVERLAPS_RANGE;
+};
+
+template <typename Dst, typename Src>
+struct StaticRangeCheck<Dst, Src, DST_UNSIGNED, SRC_SIGNED> {
+  static const DstRange value = OVERLAPS_RANGE;
+};
+
+enum RangeCheckResult {
+  TYPE_VALID = 0,      // Value can be represented by the destination type.
+  TYPE_UNDERFLOW = 1,  // Value would overflow.
+  TYPE_OVERFLOW = 2,   // Value would underflow.
+  TYPE_INVALID = 3     // Source value is invalid (i.e. NaN).
+};
+
+// This macro creates a RangeCheckResult from an upper and lower bound
+// check by taking advantage of the fact that only NaN can be out of range in
+// both directions at once.
+#define BASE_NUMERIC_RANGE_CHECK_RESULT(is_in_upper_bound, is_in_lower_bound) \
+  RangeCheckResult(((is_in_upper_bound) ? 0 : TYPE_OVERFLOW) |                \
+                   ((is_in_lower_bound) ? 0 : TYPE_UNDERFLOW))
+
+template <typename Dst,
+          typename Src,
+          DstSign IsDstSigned =
+              std::numeric_limits<Dst>::is_signed ? DST_SIGNED : DST_UNSIGNED,
+          SrcSign IsSrcSigned =
+              std::numeric_limits<Src>::is_signed ? SRC_SIGNED : SRC_UNSIGNED,
+          DstRange IsSrcRangeContained = StaticRangeCheck<Dst, Src>::value>
+struct RangeCheckImpl {};
+
+// The following templates are for ranges that must be verified at runtime. We
+// split it into checks based on signedness to avoid confusing casts and
+// compiler warnings on signed an unsigned comparisons.
+
+// Dst range always contains the result: nothing to check.
+template <typename Dst, typename Src, DstSign IsDstSigned, SrcSign IsSrcSigned>
+struct RangeCheckImpl<Dst, Src, IsDstSigned, IsSrcSigned, CONTAINS_RANGE> {
+  static constexpr RangeCheckResult Check(Src value) { return TYPE_VALID; }
+};
+
+// Signed to signed narrowing.
+template <typename Dst, typename Src>
+struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_SIGNED, OVERLAPS_RANGE> {
+  static constexpr RangeCheckResult Check(Src value) {
+    typedef std::numeric_limits<Dst> DstLimits;
+    return DstLimits::is_iec559
+               ? BASE_NUMERIC_RANGE_CHECK_RESULT(
+                     value <= static_cast<Src>(DstLimits::max()),
+                     value >= static_cast<Src>(DstLimits::max() * -1))
+               : BASE_NUMERIC_RANGE_CHECK_RESULT(
+                     value <= static_cast<Src>(DstLimits::max()),
+                     value >= static_cast<Src>(DstLimits::min()));
+  }
+};
+
+// Unsigned to unsigned narrowing.
+template <typename Dst, typename Src>
+struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> {
+  static constexpr RangeCheckResult Check(Src value) {
+    typedef std::numeric_limits<Dst> DstLimits;
+    return BASE_NUMERIC_RANGE_CHECK_RESULT(
+        value <= static_cast<Src>(DstLimits::max()), true);
+  }
+};
+
+// Unsigned to signed.
+template <typename Dst, typename Src>
+struct RangeCheckImpl<Dst, Src, DST_SIGNED, SRC_UNSIGNED, OVERLAPS_RANGE> {
+  static constexpr RangeCheckResult Check(Src value) {
+    typedef std::numeric_limits<Dst> DstLimits;
+    return sizeof(Dst) > sizeof(Src)
+               ? TYPE_VALID
+               : BASE_NUMERIC_RANGE_CHECK_RESULT(
+                     value <= static_cast<Src>(DstLimits::max()), true);
+  }
+};
+
+// Signed to unsigned.
+template <typename Dst, typename Src>
+struct RangeCheckImpl<Dst, Src, DST_UNSIGNED, SRC_SIGNED, OVERLAPS_RANGE> {
+  typedef std::numeric_limits<Dst> DstLimits;
+  typedef std::numeric_limits<Src> SrcLimits;
+  // Compare based on max_exponent, which we must compute for integrals.
+  static constexpr size_t DstMaxExponent() { return sizeof(Dst) * 8; }
+  static constexpr size_t SrcMaxExponent() {
+    return SrcLimits::is_iec559 ? SrcLimits::max_exponent
+                                : (sizeof(Src) * 8 - 1);
+  }
+  static constexpr RangeCheckResult Check(Src value) {
+    return (DstMaxExponent() >= SrcMaxExponent())
+               ? BASE_NUMERIC_RANGE_CHECK_RESULT(true,
+                                                 value >= static_cast<Src>(0))
+               : BASE_NUMERIC_RANGE_CHECK_RESULT(
+                     value <= static_cast<Src>(DstLimits::max()),
+                     value >= static_cast<Src>(0));
+  }
+};
+
+template <typename Dst, typename Src>
+inline constexpr RangeCheckResult RangeCheck(Src value) {
+  static_assert(std::numeric_limits<Src>::is_specialized,
+                "argument must be numeric");
+  static_assert(std::numeric_limits<Dst>::is_specialized,
+                "result must be numeric");
+  return RangeCheckImpl<Dst, Src>::Check(value);
+}
+
+}  // namespace internal
+}  // namespace rtc
+
+#endif  // RTC_BASE_NUMERICS_SAFE_CONVERSIONS_IMPL_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/safe_minmax.h b/third_party/libwebrtc/rtc_base/numerics/safe_minmax.h
new file mode 100644
index 0000000000..6c41dfd617
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/safe_minmax.h
@@ -0,0 +1,335 @@
+/*
+ *  Copyright 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.
+ */
+
+// Minimum and maximum
+// ===================
+//
+//   rtc::SafeMin(x, y)
+//   rtc::SafeMax(x, y)
+//
+// (These are both constexpr.)
+//
+// Accept two arguments of either any two integral or any two floating-point
+// types, and return the smaller and larger value, respectively, with no
+// truncation or wrap-around. If only one of the input types is statically
+// guaranteed to be able to represent the result, the return type is that type;
+// if either one would do, the result type is the smaller type. (One of these
+// two cases always applies.)
+//
+//   * The case with one floating-point and one integral type is not allowed,
+//     because the floating-point type will have greater range, but may not
+//     have sufficient precision to represent the integer value exactly.)
+//
+// Clamp (a.k.a. constrain to a given interval)
+// ============================================
+//
+//   rtc::SafeClamp(x, a, b)
+//
+// Accepts three arguments of any mix of integral types or any mix of
+// floating-point types, and returns the value in the closed interval [a, b]
+// that is closest to x (that is, if x < a it returns a; if x > b it returns b;
+// and if a <= x <= b it returns x). As for SafeMin() and SafeMax(), there is
+// no truncation or wrap-around. The result type
+//
+//   1. is statically guaranteed to be able to represent the result;
+//
+//   2. is no larger than the largest of the three argument types; and
+//
+//   3. has the same signedness as the type of the first argument, if this is
+//      possible without violating the First or Second Law.
+//
+// There is always at least one type that meets criteria 1 and 2. If more than
+// one type meets these criteria equally well, the result type is one of the
+// types that is smallest. Note that unlike SafeMin() and SafeMax(),
+// SafeClamp() will sometimes pick a return type that isn't the type of any of
+// its arguments.
+//
+//   * In this context, a type A is smaller than a type B if it has a smaller
+//     range; that is, if A::max() - A::min() < B::max() - B::min(). For
+//     example, int8_t < int16_t == uint16_t < int32_t, and all integral types
+//     are smaller than all floating-point types.)
+//
+//   * As for SafeMin and SafeMax, mixing integer and floating-point arguments
+//     is not allowed, because floating-point types have greater range than
+//     integer types, but do not have sufficient precision to represent the
+//     values of most integer types exactly.
+//
+// Requesting a specific return type
+// =================================
+//
+// All three functions allow callers to explicitly specify the return type as a
+// template parameter, overriding the default return type. E.g.
+//
+//   rtc::SafeMin<int>(x, y)  // returns an int
+//
+// If the requested type is statically guaranteed to be able to represent the
+// result, then everything's fine, and the return type is as requested. But if
+// the requested type is too small, a static_assert is triggered.
+
+#ifndef RTC_BASE_NUMERICS_SAFE_MINMAX_H_
+#define RTC_BASE_NUMERICS_SAFE_MINMAX_H_
+
+#include <limits>
+#include <type_traits>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/safe_compare.h"
+#include "rtc_base/type_traits.h"
+
+namespace rtc {
+
+namespace safe_minmax_impl {
+
+// Make the range of a type available via something other than a constexpr
+// function, to work around MSVC limitations. See
+// https://blogs.msdn.microsoft.com/vcblog/2015/12/02/partial-support-for-expression-sfinae-in-vs-2015-update-1/
+template <typename T>
+struct Limits {
+  static constexpr T lowest = std::numeric_limits<T>::lowest();
+  static constexpr T max = std::numeric_limits<T>::max();
+};
+
+template <typename T, bool is_enum = std::is_enum<T>::value>
+struct UnderlyingType;
+
+template <typename T>
+struct UnderlyingType<T, false> {
+  using type = T;
+};
+
+template <typename T>
+struct UnderlyingType<T, true> {
+  using type = typename std::underlying_type<T>::type;
+};
+
+// Given two types T1 and T2, find types that can hold the smallest (in
+// ::min_t) and the largest (in ::max_t) of the two values.
+template <typename T1,
+          typename T2,
+          bool int1 = IsIntlike<T1>::value,
+          bool int2 = IsIntlike<T2>::value>
+struct MType {
+  static_assert(int1 == int2,
+                "You may not mix integral and floating-point arguments");
+};
+
+// Specialization for when neither type is integral (and therefore presumably
+// floating-point).
+template <typename T1, typename T2>
+struct MType<T1, T2, false, false> {
+  using min_t = typename std::common_type<T1, T2>::type;
+  static_assert(std::is_same<min_t, T1>::value ||
+                    std::is_same<min_t, T2>::value,
+                "");
+
+  using max_t = typename std::common_type<T1, T2>::type;
+  static_assert(std::is_same<max_t, T1>::value ||
+                    std::is_same<max_t, T2>::value,
+                "");
+};
+
+// Specialization for when both types are integral.
+template <typename T1, typename T2>
+struct MType<T1, T2, true, true> {
+  // The type with the lowest minimum value. In case of a tie, the type with
+  // the lowest maximum value. In case that too is a tie, the types have the
+  // same range, and we arbitrarily pick T1.
+  using min_t = typename std::conditional<
+      SafeLt(Limits<T1>::lowest, Limits<T2>::lowest),
+      T1,
+      typename std::conditional<
+          SafeGt(Limits<T1>::lowest, Limits<T2>::lowest),
+          T2,
+          typename std::conditional<SafeLe(Limits<T1>::max, Limits<T2>::max),
+                                    T1,
+                                    T2>::type>::type>::type;
+  static_assert(std::is_same<min_t, T1>::value ||
+                    std::is_same<min_t, T2>::value,
+                "");
+
+  // The type with the highest maximum value. In case of a tie, the types have
+  // the same range (because in C++, integer types with the same maximum also
+  // have the same minimum).
+  static_assert(SafeNe(Limits<T1>::max, Limits<T2>::max) ||
+                    SafeEq(Limits<T1>::lowest, Limits<T2>::lowest),
+                "integer types with the same max should have the same min");
+  using max_t = typename std::
+      conditional<SafeGe(Limits<T1>::max, Limits<T2>::max), T1, T2>::type;
+  static_assert(std::is_same<max_t, T1>::value ||
+                    std::is_same<max_t, T2>::value,
+                "");
+};
+
+// A dummy type that we pass around at compile time but never actually use.
+// Declared but not defined.
+struct DefaultType;
+
+// ::type is A, except we fall back to B if A is DefaultType. We static_assert
+// that the chosen type can hold all values that B can hold.
+template <typename A, typename B>
+struct TypeOr {
+  using type = typename std::
+      conditional<std::is_same<A, DefaultType>::value, B, A>::type;
+  static_assert(SafeLe(Limits<type>::lowest, Limits<B>::lowest) &&
+                    SafeGe(Limits<type>::max, Limits<B>::max),
+                "The specified type isn't large enough");
+  static_assert(IsIntlike<type>::value == IsIntlike<B>::value &&
+                    std::is_floating_point<type>::value ==
+                        std::is_floating_point<type>::value,
+                "float<->int conversions not allowed");
+};
+
+}  // namespace safe_minmax_impl
+
+template <
+    typename R = safe_minmax_impl::DefaultType,
+    typename T1 = safe_minmax_impl::DefaultType,
+    typename T2 = safe_minmax_impl::DefaultType,
+    typename R2 = typename safe_minmax_impl::TypeOr<
+        R,
+        typename safe_minmax_impl::MType<
+            typename safe_minmax_impl::UnderlyingType<T1>::type,
+            typename safe_minmax_impl::UnderlyingType<T2>::type>::min_t>::type>
+constexpr R2 SafeMin(T1 a, T2 b) {
+  static_assert(IsIntlike<T1>::value || std::is_floating_point<T1>::value,
+                "The first argument must be integral or floating-point");
+  static_assert(IsIntlike<T2>::value || std::is_floating_point<T2>::value,
+                "The second argument must be integral or floating-point");
+  return SafeLt(a, b) ? static_cast<R2>(a) : static_cast<R2>(b);
+}
+
+template <
+    typename R = safe_minmax_impl::DefaultType,
+    typename T1 = safe_minmax_impl::DefaultType,
+    typename T2 = safe_minmax_impl::DefaultType,
+    typename R2 = typename safe_minmax_impl::TypeOr<
+        R,
+        typename safe_minmax_impl::MType<
+            typename safe_minmax_impl::UnderlyingType<T1>::type,
+            typename safe_minmax_impl::UnderlyingType<T2>::type>::max_t>::type>
+constexpr R2 SafeMax(T1 a, T2 b) {
+  static_assert(IsIntlike<T1>::value || std::is_floating_point<T1>::value,
+                "The first argument must be integral or floating-point");
+  static_assert(IsIntlike<T2>::value || std::is_floating_point<T2>::value,
+                "The second argument must be integral or floating-point");
+  return SafeGt(a, b) ? static_cast<R2>(a) : static_cast<R2>(b);
+}
+
+namespace safe_minmax_impl {
+
+// Given three types T, L, and H, let ::type be a suitable return value for
+// SafeClamp(T, L, H). See the docs at the top of this file for details.
+template <typename T,
+          typename L,
+          typename H,
+          bool int1 = IsIntlike<T>::value,
+          bool int2 = IsIntlike<L>::value,
+          bool int3 = IsIntlike<H>::value>
+struct ClampType {
+  static_assert(int1 == int2 && int1 == int3,
+                "You may not mix integral and floating-point arguments");
+};
+
+// Specialization for when all three types are floating-point.
+template <typename T, typename L, typename H>
+struct ClampType<T, L, H, false, false, false> {
+  using type = typename std::common_type<T, L, H>::type;
+};
+
+// Specialization for when all three types are integral.
+template <typename T, typename L, typename H>
+struct ClampType<T, L, H, true, true, true> {
+ private:
+  // Range of the return value. The return type must be able to represent this
+  // full range.
+  static constexpr auto r_min =
+      SafeMax(Limits<L>::lowest, SafeMin(Limits<H>::lowest, Limits<T>::lowest));
+  static constexpr auto r_max =
+      SafeMin(Limits<H>::max, SafeMax(Limits<L>::max, Limits<T>::max));
+
+  // Is the given type an acceptable return type? (That is, can it represent
+  // all possible return values, and is it no larger than the largest of the
+  // input types?)
+  template <typename A>
+  struct AcceptableType {
+   private:
+    static constexpr bool not_too_large = sizeof(A) <= sizeof(L) ||
+                                          sizeof(A) <= sizeof(H) ||
+                                          sizeof(A) <= sizeof(T);
+    static constexpr bool range_contained =
+        SafeLe(Limits<A>::lowest, r_min) && SafeLe(r_max, Limits<A>::max);
+
+   public:
+    static constexpr bool value = not_too_large && range_contained;
+  };
+
+  using best_signed_type = typename std::conditional<
+      AcceptableType<int8_t>::value,
+      int8_t,
+      typename std::conditional<
+          AcceptableType<int16_t>::value,
+          int16_t,
+          typename std::conditional<AcceptableType<int32_t>::value,
+                                    int32_t,
+                                    int64_t>::type>::type>::type;
+
+  using best_unsigned_type = typename std::conditional<
+      AcceptableType<uint8_t>::value,
+      uint8_t,
+      typename std::conditional<
+          AcceptableType<uint16_t>::value,
+          uint16_t,
+          typename std::conditional<AcceptableType<uint32_t>::value,
+                                    uint32_t,
+                                    uint64_t>::type>::type>::type;
+
+ public:
+  // Pick the best type, preferring the same signedness as T but falling back
+  // to the other one if necessary.
+  using type = typename std::conditional<
+      std::is_signed<T>::value,
+      typename std::conditional<AcceptableType<best_signed_type>::value,
+                                best_signed_type,
+                                best_unsigned_type>::type,
+      typename std::conditional<AcceptableType<best_unsigned_type>::value,
+                                best_unsigned_type,
+                                best_signed_type>::type>::type;
+  static_assert(AcceptableType<type>::value, "");
+};
+
+}  // namespace safe_minmax_impl
+
+template <
+    typename R = safe_minmax_impl::DefaultType,
+    typename T = safe_minmax_impl::DefaultType,
+    typename L = safe_minmax_impl::DefaultType,
+    typename H = safe_minmax_impl::DefaultType,
+    typename R2 = typename safe_minmax_impl::TypeOr<
+        R,
+        typename safe_minmax_impl::ClampType<
+            typename safe_minmax_impl::UnderlyingType<T>::type,
+            typename safe_minmax_impl::UnderlyingType<L>::type,
+            typename safe_minmax_impl::UnderlyingType<H>::type>::type>::type>
+R2 SafeClamp(T x, L min, H max) {
+  static_assert(IsIntlike<H>::value || std::is_floating_point<H>::value,
+                "The first argument must be integral or floating-point");
+  static_assert(IsIntlike<T>::value || std::is_floating_point<T>::value,
+                "The second argument must be integral or floating-point");
+  static_assert(IsIntlike<L>::value || std::is_floating_point<L>::value,
+                "The third argument must be integral or floating-point");
+  RTC_DCHECK_LE(min, max);
+  return SafeLe(x, min)
+             ? static_cast<R2>(min)
+             : SafeGe(x, max) ? static_cast<R2>(max) : static_cast<R2>(x);
+}
+
+}  // namespace rtc
+
+#endif  // RTC_BASE_NUMERICS_SAFE_MINMAX_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/safe_minmax_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/safe_minmax_unittest.cc
new file mode 100644
index 0000000000..c52b3f93dc
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/safe_minmax_unittest.cc
@@ -0,0 +1,345 @@
+/*
+ *  Copyright 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.
+ */
+
+#include "rtc_base/numerics/safe_minmax.h"
+
+#include <algorithm>
+#include <limits>
+
+#include "test/gtest.h"
+
+namespace rtc {
+
+namespace {
+
+// Functions that check that SafeMin(), SafeMax(), and SafeClamp() return the
+// specified type. The functions that end in "R" use an explicitly given return
+// type.
+
+template <typename T1, typename T2, typename Tmin, typename Tmax>
+constexpr bool TypeCheckMinMax() {
+  return std::is_same<decltype(SafeMin(std::declval<T1>(), std::declval<T2>())),
+                      Tmin>::value &&
+         std::is_same<decltype(SafeMax(std::declval<T1>(), std::declval<T2>())),
+                      Tmax>::value;
+}
+
+template <typename T1, typename T2, typename R>
+constexpr bool TypeCheckMinR() {
+  return std::is_same<
+      decltype(SafeMin<R>(std::declval<T1>(), std::declval<T2>())), R>::value;
+}
+
+template <typename T1, typename T2, typename R>
+constexpr bool TypeCheckMaxR() {
+  return std::is_same<
+      decltype(SafeMax<R>(std::declval<T1>(), std::declval<T2>())), R>::value;
+}
+
+template <typename T, typename L, typename H, typename R>
+constexpr bool TypeCheckClamp() {
+  return std::is_same<decltype(SafeClamp(std::declval<T>(), std::declval<L>(),
+                                         std::declval<H>())),
+                      R>::value;
+}
+
+template <typename T, typename L, typename H, typename R>
+constexpr bool TypeCheckClampR() {
+  return std::is_same<decltype(SafeClamp<R>(std::declval<T>(),
+                                            std::declval<L>(),
+                                            std::declval<H>())),
+                      R>::value;
+}
+
+// clang-format off
+
+// SafeMin/SafeMax: Check that all combinations of signed/unsigned 8/64 bits
+// give the correct default result type.
+static_assert(TypeCheckMinMax<  int8_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckMinMax<  int8_t,  uint8_t,   int8_t,  uint8_t>(), "");
+static_assert(TypeCheckMinMax<  int8_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckMinMax<  int8_t, uint64_t,   int8_t, uint64_t>(), "");
+static_assert(TypeCheckMinMax< uint8_t,   int8_t,   int8_t,  uint8_t>(), "");
+static_assert(TypeCheckMinMax< uint8_t,  uint8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckMinMax< uint8_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckMinMax< uint8_t, uint64_t,  uint8_t, uint64_t>(), "");
+static_assert(TypeCheckMinMax< int64_t,   int8_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckMinMax< int64_t,  uint8_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckMinMax< int64_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckMinMax< int64_t, uint64_t,  int64_t, uint64_t>(), "");
+static_assert(TypeCheckMinMax<uint64_t,   int8_t,   int8_t, uint64_t>(), "");
+static_assert(TypeCheckMinMax<uint64_t,  uint8_t,  uint8_t, uint64_t>(), "");
+static_assert(TypeCheckMinMax<uint64_t,  int64_t,  int64_t, uint64_t>(), "");
+static_assert(TypeCheckMinMax<uint64_t, uint64_t, uint64_t, uint64_t>(), "");
+
+// SafeClamp: Check that all combinations of signed/unsigned 8/64 bits give the
+// correct result type.
+static_assert(TypeCheckClamp<  int8_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,   int8_t,  uint8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,   int8_t,  int64_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,   int8_t, uint64_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  uint8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  uint8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  uint8_t,  int64_t,  int16_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  uint8_t, uint64_t,  int16_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  int64_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  int64_t,  uint8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<  int8_t,  int64_t, uint64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<  int8_t, uint64_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<  int8_t, uint64_t,  uint8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp<  int8_t, uint64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<  int8_t, uint64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,   int8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,   int8_t,  int64_t,  int16_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,   int8_t, uint64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  uint8_t,   int8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  uint8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  uint8_t,  int64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  uint8_t, uint64_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  int64_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  int64_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< uint8_t,  int64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp< uint8_t, uint64_t,   int8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t, uint64_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp< uint8_t, uint64_t,  int64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp< uint8_t, uint64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< int64_t,   int8_t,  uint8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp< int64_t,   int8_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,   int8_t, uint64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  uint8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  uint8_t,  uint8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  uint8_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  uint8_t, uint64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  int64_t,   int8_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  int64_t,  uint8_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t,  int64_t, uint64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t, uint64_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp< int64_t, uint64_t,  uint8_t,  int16_t>(), "");
+static_assert(TypeCheckClamp< int64_t, uint64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp< int64_t, uint64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,   int8_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,   int8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,   int8_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,   int8_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  uint8_t,   int8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  uint8_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  uint8_t,  int64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  uint8_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  int64_t,   int8_t,   int8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  int64_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  int64_t,  int64_t,  int64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t,  int64_t, uint64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t, uint64_t,   int8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t, uint64_t,  uint8_t,  uint8_t>(), "");
+static_assert(TypeCheckClamp<uint64_t, uint64_t,  int64_t, uint64_t>(), "");
+static_assert(TypeCheckClamp<uint64_t, uint64_t, uint64_t, uint64_t>(), "");
+
+enum DefaultE { kFoo = -17 };
+enum UInt8E : uint8_t { kBar = 17 };
+
+// SafeMin/SafeMax: Check that we can use enum types.
+static_assert(TypeCheckMinMax<unsigned, unsigned, unsigned, unsigned>(), "");
+static_assert(TypeCheckMinMax<unsigned, DefaultE,      int, unsigned>(), "");
+static_assert(TypeCheckMinMax<unsigned,   UInt8E,  uint8_t, unsigned>(), "");
+static_assert(TypeCheckMinMax<DefaultE, unsigned,      int, unsigned>(), "");
+static_assert(TypeCheckMinMax<DefaultE, DefaultE,      int,      int>(), "");
+static_assert(TypeCheckMinMax<DefaultE,   UInt8E,      int,      int>(), "");
+static_assert(TypeCheckMinMax<  UInt8E, unsigned,  uint8_t, unsigned>(), "");
+static_assert(TypeCheckMinMax<  UInt8E, DefaultE,     int,       int>(), "");
+static_assert(TypeCheckMinMax<  UInt8E,   UInt8E,  uint8_t,  uint8_t>(), "");
+
+// SafeClamp: Check that we can use enum types.
+static_assert(TypeCheckClamp<unsigned, unsigned, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned, unsigned, DefaultE, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned, unsigned,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<unsigned, DefaultE, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned, DefaultE, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<unsigned, DefaultE,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<unsigned,   UInt8E, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned,   UInt8E, DefaultE, unsigned>(), "");
+static_assert(TypeCheckClamp<unsigned,   UInt8E,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<DefaultE, unsigned, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<DefaultE, unsigned, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE, unsigned,   UInt8E,  int16_t>(), "");
+static_assert(TypeCheckClamp<DefaultE, DefaultE, unsigned,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE, DefaultE, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE, DefaultE,   UInt8E,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE,   UInt8E, unsigned,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE,   UInt8E, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<DefaultE,   UInt8E,   UInt8E,  int16_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E, unsigned, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<  UInt8E, unsigned, DefaultE, unsigned>(), "");
+static_assert(TypeCheckClamp<  UInt8E, unsigned,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E, DefaultE, unsigned, unsigned>(), "");
+static_assert(TypeCheckClamp<  UInt8E, DefaultE, DefaultE,      int>(), "");
+static_assert(TypeCheckClamp<  UInt8E, DefaultE,   UInt8E,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E,   UInt8E, unsigned,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E,   UInt8E, DefaultE,  uint8_t>(), "");
+static_assert(TypeCheckClamp<  UInt8E,   UInt8E,   UInt8E,  uint8_t>(), "");
+
+using ld = long double;
+
+// SafeMin/SafeMax: Check that all floating-point combinations give the
+// correct result type.
+static_assert(TypeCheckMinMax< float,  float,  float,  float>(), "");
+static_assert(TypeCheckMinMax< float, double, double, double>(), "");
+static_assert(TypeCheckMinMax< float,     ld,     ld,     ld>(), "");
+static_assert(TypeCheckMinMax<double,  float, double, double>(), "");
+static_assert(TypeCheckMinMax<double, double, double, double>(), "");
+static_assert(TypeCheckMinMax<double,     ld,     ld,     ld>(), "");
+static_assert(TypeCheckMinMax<    ld,  float,     ld,     ld>(), "");
+static_assert(TypeCheckMinMax<    ld, double,     ld,     ld>(), "");
+static_assert(TypeCheckMinMax<    ld,     ld,     ld,     ld>(), "");
+
+// SafeClamp: Check that all floating-point combinations give the correct
+// result type.
+static_assert(TypeCheckClamp< float,  float,  float,  float>(), "");
+static_assert(TypeCheckClamp< float,  float, double, double>(), "");
+static_assert(TypeCheckClamp< float,  float,     ld,     ld>(), "");
+static_assert(TypeCheckClamp< float, double,  float, double>(), "");
+static_assert(TypeCheckClamp< float, double, double, double>(), "");
+static_assert(TypeCheckClamp< float, double,     ld,     ld>(), "");
+static_assert(TypeCheckClamp< float,     ld,  float,     ld>(), "");
+static_assert(TypeCheckClamp< float,     ld, double,     ld>(), "");
+static_assert(TypeCheckClamp< float,     ld,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<double,  float,  float, double>(), "");
+static_assert(TypeCheckClamp<double,  float, double, double>(), "");
+static_assert(TypeCheckClamp<double,  float,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<double, double,  float, double>(), "");
+static_assert(TypeCheckClamp<double, double, double, double>(), "");
+static_assert(TypeCheckClamp<double, double,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<double,     ld,  float,     ld>(), "");
+static_assert(TypeCheckClamp<double,     ld, double,     ld>(), "");
+static_assert(TypeCheckClamp<double,     ld,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,  float,  float,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,  float, double,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,  float,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<    ld, double,  float,     ld>(), "");
+static_assert(TypeCheckClamp<    ld, double, double,     ld>(), "");
+static_assert(TypeCheckClamp<    ld, double,     ld,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,     ld,  float,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,     ld, double,     ld>(), "");
+static_assert(TypeCheckClamp<    ld,     ld,     ld,     ld>(), "");
+
+// clang-format on
+
+// SafeMin/SafeMax: Check some cases of explicitly specified return type. The
+// commented-out lines give compilation errors due to the requested return type
+// being too small or requiring an int<->float conversion.
+static_assert(TypeCheckMinR<int8_t, int8_t, int16_t>(), "");
+// static_assert(TypeCheckMinR<int8_t, int8_t, float>(), "");
+static_assert(TypeCheckMinR<uint32_t, uint64_t, uint32_t>(), "");
+// static_assert(TypeCheckMaxR<uint64_t, float, float>(), "");
+// static_assert(TypeCheckMaxR<uint64_t, double, float>(), "");
+static_assert(TypeCheckMaxR<uint32_t, int32_t, uint32_t>(), "");
+// static_assert(TypeCheckMaxR<uint32_t, int32_t, int32_t>(), "");
+
+// SafeClamp: Check some cases of explicitly specified return type. The
+// commented-out lines give compilation errors due to the requested return type
+// being too small.
+static_assert(TypeCheckClampR<int16_t, int8_t, uint8_t, int16_t>(), "");
+static_assert(TypeCheckClampR<int16_t, int8_t, uint8_t, int32_t>(), "");
+// static_assert(TypeCheckClampR<int16_t, int8_t, uint8_t, uint32_t>(), "");
+
+template <typename T1, typename T2, typename Tmin, typename Tmax>
+constexpr bool CheckMinMax(T1 a, T2 b, Tmin min, Tmax max) {
+  return TypeCheckMinMax<T1, T2, Tmin, Tmax>() && SafeMin(a, b) == min &&
+         SafeMax(a, b) == max;
+}
+
+template <typename T, typename L, typename H, typename R>
+bool CheckClamp(T x, L min, H max, R clamped) {
+  return TypeCheckClamp<T, L, H, R>() && SafeClamp(x, min, max) == clamped;
+}
+
+// SafeMin/SafeMax: Check a few values.
+static_assert(CheckMinMax(int8_t{1}, int8_t{-1}, int8_t{-1}, int8_t{1}), "");
+static_assert(CheckMinMax(uint8_t{1}, int8_t{-1}, int8_t{-1}, uint8_t{1}), "");
+static_assert(CheckMinMax(uint8_t{5}, uint64_t{2}, uint8_t{2}, uint64_t{5}),
+              "");
+static_assert(CheckMinMax(std::numeric_limits<int32_t>::min(),
+                          std::numeric_limits<uint32_t>::max(),
+                          std::numeric_limits<int32_t>::min(),
+                          std::numeric_limits<uint32_t>::max()),
+              "");
+static_assert(CheckMinMax(std::numeric_limits<int32_t>::min(),
+                          std::numeric_limits<uint16_t>::max(),
+                          std::numeric_limits<int32_t>::min(),
+                          int32_t{std::numeric_limits<uint16_t>::max()}),
+              "");
+// static_assert(CheckMinMax(1.f, 2, 1.f, 2.f), "");
+static_assert(CheckMinMax(1.f, 0.0, 0.0, 1.0), "");
+
+// SafeClamp: Check a few values.
+TEST(SafeMinmaxTest, Clamp) {
+  EXPECT_TRUE(CheckClamp(int32_t{-1000000}, std::numeric_limits<int16_t>::min(),
+                         std::numeric_limits<int16_t>::max(),
+                         std::numeric_limits<int16_t>::min()));
+  EXPECT_TRUE(CheckClamp(uint32_t{1000000}, std::numeric_limits<int16_t>::min(),
+                         std::numeric_limits<int16_t>::max(),
+                         std::numeric_limits<int16_t>::max()));
+  EXPECT_TRUE(CheckClamp(3.f, -1.0, 1.f, 1.0));
+  EXPECT_TRUE(CheckClamp(3.0, -1.f, 1.f, 1.0));
+}
+
+}  // namespace
+
+// These functions aren't used in the tests, but it's useful to look at the
+// compiler output for them, and verify that (1) the same-signedness Test*Safe
+// functions result in exactly the same code as their Test*Ref counterparts,
+// and that (2) the mixed-signedness Test*Safe functions have just a few extra
+// arithmetic and logic instructions (but no extra control flow instructions).
+
+// clang-format off
+int32_t  TestMinRef(  int32_t a,  int32_t b) { return std::min(a, b); }
+uint32_t TestMinRef( uint32_t a, uint32_t b) { return std::min(a, b); }
+int32_t  TestMinSafe( int32_t a,  int32_t b) { return SafeMin(a, b); }
+int32_t  TestMinSafe( int32_t a, uint32_t b) { return SafeMin(a, b); }
+int32_t  TestMinSafe(uint32_t a,  int32_t b) { return SafeMin(a, b); }
+uint32_t TestMinSafe(uint32_t a, uint32_t b) { return SafeMin(a, b); }
+// clang-format on
+
+int32_t TestClampRef(int32_t x, int32_t a, int32_t b) {
+  return std::max(a, std::min(x, b));
+}
+uint32_t TestClampRef(uint32_t x, uint32_t a, uint32_t b) {
+  return std::max(a, std::min(x, b));
+}
+int32_t TestClampSafe(int32_t x, int32_t a, int32_t b) {
+  return SafeClamp(x, a, b);
+}
+int32_t TestClampSafe(int32_t x, int32_t a, uint32_t b) {
+  return SafeClamp(x, a, b);
+}
+int32_t TestClampSafe(int32_t x, uint32_t a, int32_t b) {
+  return SafeClamp(x, a, b);
+}
+uint32_t TestClampSafe(int32_t x, uint32_t a, uint32_t b) {
+  return SafeClamp(x, a, b);
+}
+int32_t TestClampSafe(uint32_t x, int32_t a, int32_t b) {
+  return SafeClamp(x, a, b);
+}
+uint32_t TestClampSafe(uint32_t x, int32_t a, uint32_t b) {
+  return SafeClamp(x, a, b);
+}
+int32_t TestClampSafe(uint32_t x, uint32_t a, int32_t b) {
+  return SafeClamp(x, a, b);
+}
+uint32_t TestClampSafe(uint32_t x, uint32_t a, uint32_t b) {
+  return SafeClamp(x, a, b);
+}
+
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/sample_counter.cc b/third_party/libwebrtc/rtc_base/numerics/sample_counter.cc
new file mode 100644
index 0000000000..16a8e25098
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sample_counter.cc
@@ -0,0 +1,109 @@
+/*
+ *  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 "rtc_base/numerics/sample_counter.h"
+
+#include <limits>
+
+#include "rtc_base/checks.h"
+#include "rtc_base/numerics/safe_conversions.h"
+
+namespace rtc {
+
+SampleCounter::SampleCounter() = default;
+SampleCounter::~SampleCounter() = default;
+
+void SampleCounter::Add(int sample) {
+  if (sum_ > 0) {
+    RTC_DCHECK_LE(sample, std::numeric_limits<int64_t>::max() - sum_);
+  } else {
+    RTC_DCHECK_GE(sample, std::numeric_limits<int64_t>::min() - sum_);
+  }
+  sum_ += sample;
+  ++num_samples_;
+  if (!max_ || sample > *max_) {
+    max_ = sample;
+  }
+}
+
+void SampleCounter::Add(const SampleCounter& other) {
+  if (sum_ > 0) {
+    RTC_DCHECK_LE(other.sum_, std::numeric_limits<int64_t>::max() - sum_);
+  } else {
+    RTC_DCHECK_GE(other.sum_, std::numeric_limits<int64_t>::min() - sum_);
+  }
+  sum_ += other.sum_;
+  RTC_DCHECK_LE(other.num_samples_,
+                std::numeric_limits<int64_t>::max() - num_samples_);
+  num_samples_ += other.num_samples_;
+  if (other.max_ && (!max_ || *max_ < *other.max_))
+    max_ = other.max_;
+}
+
+absl::optional<int> SampleCounter::Avg(int64_t min_required_samples) const {
+  RTC_DCHECK_GT(min_required_samples, 0);
+  if (num_samples_ < min_required_samples)
+    return absl::nullopt;
+  return rtc::dchecked_cast<int>(sum_ / num_samples_);
+}
+
+absl::optional<int> SampleCounter::Max() const {
+  return max_;
+}
+
+absl::optional<int64_t> SampleCounter::Sum(int64_t min_required_samples) const {
+  RTC_DCHECK_GT(min_required_samples, 0);
+  if (num_samples_ < min_required_samples)
+    return absl::nullopt;
+  return sum_;
+}
+
+int64_t SampleCounter::NumSamples() const {
+  return num_samples_;
+}
+
+void SampleCounter::Reset() {
+  *this = {};
+}
+
+SampleCounterWithVariance::SampleCounterWithVariance() = default;
+SampleCounterWithVariance::~SampleCounterWithVariance() = default;
+
+absl::optional<int64_t> SampleCounterWithVariance::Variance(
+    int64_t min_required_samples) const {
+  RTC_DCHECK_GT(min_required_samples, 0);
+  if (num_samples_ < min_required_samples)
+    return absl::nullopt;
+  // E[(x-mean)^2] = E[x^2] - mean^2
+  int64_t mean = sum_ / num_samples_;
+  return sum_squared_ / num_samples_ - mean * mean;
+}
+
+void SampleCounterWithVariance::Add(int sample) {
+  SampleCounter::Add(sample);
+  // Prevent overflow in squaring.
+  RTC_DCHECK_GT(sample, std::numeric_limits<int32_t>::min());
+  RTC_DCHECK_LE(int64_t{sample} * sample,
+                std::numeric_limits<int64_t>::max() - sum_squared_);
+  sum_squared_ += int64_t{sample} * sample;
+}
+
+void SampleCounterWithVariance::Add(const SampleCounterWithVariance& other) {
+  SampleCounter::Add(other);
+  RTC_DCHECK_LE(other.sum_squared_,
+                std::numeric_limits<int64_t>::max() - sum_squared_);
+  sum_squared_ += other.sum_squared_;
+}
+
+void SampleCounterWithVariance::Reset() {
+  *this = {};
+}
+
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/sample_counter.h b/third_party/libwebrtc/rtc_base/numerics/sample_counter.h
new file mode 100644
index 0000000000..717a1afbcf
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sample_counter.h
@@ -0,0 +1,58 @@
+/*
+ *  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.
+ */
+
+#ifndef RTC_BASE_NUMERICS_SAMPLE_COUNTER_H_
+#define RTC_BASE_NUMERICS_SAMPLE_COUNTER_H_
+
+#include <stdint.h>
+
+#include "absl/types/optional.h"
+
+namespace rtc {
+
+// Simple utility class for counting basic statistics (max./avg./variance) on
+// stream of samples.
+class SampleCounter {
+ public:
+  SampleCounter();
+  ~SampleCounter();
+  void Add(int sample);
+  absl::optional<int> Avg(int64_t min_required_samples) const;
+  absl::optional<int> Max() const;
+  absl::optional<int64_t> Sum(int64_t min_required_samples) const;
+  int64_t NumSamples() const;
+  void Reset();
+  // Adds all the samples from the `other` SampleCounter as if they were all
+  // individually added using `Add(int)` method.
+  void Add(const SampleCounter& other);
+
+ protected:
+  int64_t sum_ = 0;
+  int64_t num_samples_ = 0;
+  absl::optional<int> max_;
+};
+
+class SampleCounterWithVariance : public SampleCounter {
+ public:
+  SampleCounterWithVariance();
+  ~SampleCounterWithVariance();
+  void Add(int sample);
+  absl::optional<int64_t> Variance(int64_t min_required_samples) const;
+  void Reset();
+  // Adds all the samples from the `other` SampleCounter as if they were all
+  // individually added using `Add(int)` method.
+  void Add(const SampleCounterWithVariance& other);
+
+ private:
+  int64_t sum_squared_ = 0;
+};
+
+}  // namespace rtc
+#endif  // RTC_BASE_NUMERICS_SAMPLE_COUNTER_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/sample_counter_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/sample_counter_unittest.cc
new file mode 100644
index 0000000000..14b0573de9
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sample_counter_unittest.cc
@@ -0,0 +1,80 @@
+/*
+ *  Copyright 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 "rtc_base/numerics/sample_counter.h"
+
+#include <initializer_list>
+
+#include "test/gmock.h"
+#include "test/gtest.h"
+
+using ::testing::Eq;
+
+namespace rtc {
+
+TEST(SampleCounterTest, ProcessesNoSamples) {
+  constexpr int kMinSamples = 1;
+  SampleCounter counter;
+  EXPECT_THAT(counter.Avg(kMinSamples), Eq(absl::nullopt));
+  EXPECT_THAT(counter.Max(), Eq(absl::nullopt));
+}
+
+TEST(SampleCounterTest, NotEnoughSamples) {
+  constexpr int kMinSamples = 6;
+  SampleCounter counter;
+  for (int value : {1, 2, 3, 4, 5}) {
+    counter.Add(value);
+  }
+  EXPECT_THAT(counter.Avg(kMinSamples), Eq(absl::nullopt));
+  EXPECT_THAT(counter.Sum(kMinSamples), Eq(absl::nullopt));
+  EXPECT_THAT(counter.Max(), Eq(5));
+}
+
+TEST(SampleCounterTest, EnoughSamples) {
+  constexpr int kMinSamples = 5;
+  SampleCounter counter;
+  for (int value : {1, 2, 3, 4, 5}) {
+    counter.Add(value);
+  }
+  EXPECT_THAT(counter.Avg(kMinSamples), Eq(3));
+  EXPECT_THAT(counter.Sum(kMinSamples), Eq(15));
+  EXPECT_THAT(counter.Max(), Eq(5));
+}
+
+TEST(SampleCounterTest, ComputesVariance) {
+  constexpr int kMinSamples = 5;
+  SampleCounterWithVariance counter;
+  for (int value : {1, 2, 3, 4, 5}) {
+    counter.Add(value);
+  }
+  EXPECT_THAT(counter.Variance(kMinSamples), Eq(2));
+}
+
+TEST(SampleCounterTest, AggregatesTwoCounters) {
+  constexpr int kMinSamples = 5;
+  SampleCounterWithVariance counter1;
+  for (int value : {1, 2, 3}) {
+    counter1.Add(value);
+  }
+  SampleCounterWithVariance counter2;
+  for (int value : {4, 5}) {
+    counter2.Add(value);
+  }
+  // Before aggregation there is not enough samples.
+  EXPECT_THAT(counter1.Avg(kMinSamples), Eq(absl::nullopt));
+  EXPECT_THAT(counter1.Variance(kMinSamples), Eq(absl::nullopt));
+  // Aggregate counter2 in counter1.
+  counter1.Add(counter2);
+  EXPECT_THAT(counter1.Avg(kMinSamples), Eq(3));
+  EXPECT_THAT(counter1.Max(), Eq(5));
+  EXPECT_THAT(counter1.Variance(kMinSamples), Eq(2));
+}
+
+}  // namespace rtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/sample_stats.cc b/third_party/libwebrtc/rtc_base/numerics/sample_stats.cc
new file mode 100644
index 0000000000..6000b2b88f
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sample_stats.cc
@@ -0,0 +1,152 @@
+/*
+ *  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.
+ */
+#include "rtc_base/numerics/sample_stats.h"
+
+namespace webrtc {
+
+double SampleStats<double>::Max() {
+  if (IsEmpty())
+    return INFINITY;
+  return GetMax();
+}
+
+double SampleStats<double>::Mean() {
+  if (IsEmpty())
+    return 0;
+  return GetAverage();
+}
+
+double SampleStats<double>::Median() {
+  return Quantile(0.5);
+}
+
+double SampleStats<double>::Quantile(double quantile) {
+  if (IsEmpty())
+    return 0;
+  return GetPercentile(quantile);
+}
+
+double SampleStats<double>::Min() {
+  if (IsEmpty())
+    return -INFINITY;
+  return GetMin();
+}
+
+double SampleStats<double>::Variance() {
+  if (IsEmpty())
+    return 0;
+  return GetVariance();
+}
+
+double SampleStats<double>::StandardDeviation() {
+  return sqrt(Variance());
+}
+
+int SampleStats<double>::Count() {
+  return static_cast<int>(GetSamples().size());
+}
+
+void SampleStats<TimeDelta>::AddSample(TimeDelta delta) {
+  RTC_DCHECK(delta.IsFinite());
+  stats_.AddSample(delta.seconds<double>());
+}
+
+void SampleStats<TimeDelta>::AddSampleMs(double delta_ms) {
+  AddSample(TimeDelta::Millis(delta_ms));
+}
+void SampleStats<TimeDelta>::AddSamples(const SampleStats<TimeDelta>& other) {
+  stats_.AddSamples(other.stats_);
+}
+
+bool SampleStats<TimeDelta>::IsEmpty() {
+  return stats_.IsEmpty();
+}
+
+TimeDelta SampleStats<TimeDelta>::Max() {
+  return TimeDelta::Seconds(stats_.Max());
+}
+
+TimeDelta SampleStats<TimeDelta>::Mean() {
+  return TimeDelta::Seconds(stats_.Mean());
+}
+
+TimeDelta SampleStats<TimeDelta>::Median() {
+  return Quantile(0.5);
+}
+
+TimeDelta SampleStats<TimeDelta>::Quantile(double quantile) {
+  return TimeDelta::Seconds(stats_.Quantile(quantile));
+}
+
+TimeDelta SampleStats<TimeDelta>::Min() {
+  return TimeDelta::Seconds(stats_.Min());
+}
+
+TimeDelta SampleStats<TimeDelta>::Variance() {
+  return TimeDelta::Seconds(stats_.Variance());
+}
+
+TimeDelta SampleStats<TimeDelta>::StandardDeviation() {
+  return TimeDelta::Seconds(stats_.StandardDeviation());
+}
+
+int SampleStats<TimeDelta>::Count() {
+  return stats_.Count();
+}
+
+void SampleStats<DataRate>::AddSample(DataRate sample) {
+  stats_.AddSample(sample.bps<double>());
+}
+
+void SampleStats<DataRate>::AddSampleBps(double rate_bps) {
+  stats_.AddSample(rate_bps);
+}
+
+void SampleStats<DataRate>::AddSamples(const SampleStats<DataRate>& other) {
+  stats_.AddSamples(other.stats_);
+}
+
+bool SampleStats<DataRate>::IsEmpty() {
+  return stats_.IsEmpty();
+}
+
+DataRate SampleStats<DataRate>::Max() {
+  return DataRate::BitsPerSec(stats_.Max());
+}
+
+DataRate SampleStats<DataRate>::Mean() {
+  return DataRate::BitsPerSec(stats_.Mean());
+}
+
+DataRate SampleStats<DataRate>::Median() {
+  return Quantile(0.5);
+}
+
+DataRate SampleStats<DataRate>::Quantile(double quantile) {
+  return DataRate::BitsPerSec(stats_.Quantile(quantile));
+}
+
+DataRate SampleStats<DataRate>::Min() {
+  return DataRate::BitsPerSec(stats_.Min());
+}
+
+DataRate SampleStats<DataRate>::Variance() {
+  return DataRate::BitsPerSec(stats_.Variance());
+}
+
+DataRate SampleStats<DataRate>::StandardDeviation() {
+  return DataRate::BitsPerSec(stats_.StandardDeviation());
+}
+
+int SampleStats<DataRate>::Count() {
+  return stats_.Count();
+}
+
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/sample_stats.h b/third_party/libwebrtc/rtc_base/numerics/sample_stats.h
new file mode 100644
index 0000000000..39af1c6a37
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sample_stats.h
@@ -0,0 +1,77 @@
+/*
+ *  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 RTC_BASE_NUMERICS_SAMPLE_STATS_H_
+#define RTC_BASE_NUMERICS_SAMPLE_STATS_H_
+
+#include "api/numerics/samples_stats_counter.h"
+#include "api/units/data_rate.h"
+#include "api/units/time_delta.h"
+#include "api/units/timestamp.h"
+
+namespace webrtc {
+template <typename T>
+class SampleStats;
+
+// TODO(srte): Merge this implementation with SamplesStatsCounter.
+template <>
+class SampleStats<double> : public SamplesStatsCounter {
+ public:
+  double Max();
+  double Mean();
+  double Median();
+  double Quantile(double quantile);
+  double Min();
+  double Variance();
+  double StandardDeviation();
+  int Count();
+};
+
+template <>
+class SampleStats<TimeDelta> {
+ public:
+  void AddSample(TimeDelta delta);
+  void AddSampleMs(double delta_ms);
+  void AddSamples(const SampleStats<TimeDelta>& other);
+  bool IsEmpty();
+  TimeDelta Max();
+  TimeDelta Mean();
+  TimeDelta Median();
+  TimeDelta Quantile(double quantile);
+  TimeDelta Min();
+  TimeDelta Variance();
+  TimeDelta StandardDeviation();
+  int Count();
+
+ private:
+  SampleStats<double> stats_;
+};
+
+template <>
+class SampleStats<DataRate> {
+ public:
+  void AddSample(DataRate rate);
+  void AddSampleBps(double rate_bps);
+  void AddSamples(const SampleStats<DataRate>& other);
+  bool IsEmpty();
+  DataRate Max();
+  DataRate Mean();
+  DataRate Median();
+  DataRate Quantile(double quantile);
+  DataRate Min();
+  DataRate Variance();
+  DataRate StandardDeviation();
+  int Count();
+
+ private:
+  SampleStats<double> stats_;
+};
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_SAMPLE_STATS_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/sequence_number_unwrapper.h b/third_party/libwebrtc/rtc_base/numerics/sequence_number_unwrapper.h
new file mode 100644
index 0000000000..d741b5c910
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sequence_number_unwrapper.h
@@ -0,0 +1,80 @@
+/*
+ *  Copyright (c) 2022 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_SEQUENCE_NUMBER_UNWRAPPER_H_
+#define RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UNWRAPPER_H_
+
+#include <stdint.h>
+
+#include <limits>
+
+#include "absl/types/optional.h"
+#include "rtc_base/numerics/sequence_number_util.h"
+
+namespace webrtc {
+
+// A sequence number unwrapper where the first unwrapped value equals the
+// first value being unwrapped.
+template <typename T, T M = 0>
+class SeqNumUnwrapper {
+  static_assert(
+      std::is_unsigned<T>::value &&
+          std::numeric_limits<T>::max() < std::numeric_limits<int64_t>::max(),
+      "Type unwrapped must be an unsigned integer smaller than int64_t.");
+
+ public:
+  // Unwraps `value` and updates the internal state of the unwrapper.
+  int64_t Unwrap(T value) {
+    if (!last_value_) {
+      last_unwrapped_ = {value};
+    } else {
+      last_unwrapped_ += Delta(*last_value_, value);
+    }
+
+    last_value_ = value;
+    return last_unwrapped_;
+  }
+
+  // Returns the `value` without updating the internal state of the unwrapper.
+  int64_t PeekUnwrap(T value) const {
+    if (!last_value_) {
+      return value;
+    }
+    return last_unwrapped_ + Delta(*last_value_, value);
+  }
+
+  // Resets the unwrapper to its initial state. Unwrapped sequence numbers will
+  // being at 0 after resetting.
+  void Reset() {
+    last_unwrapped_ = 0;
+    last_value_.reset();
+  }
+
+ private:
+  static int64_t Delta(T last_value, T new_value) {
+    constexpr int64_t kBackwardAdjustment =
+        M == 0 ? int64_t{std::numeric_limits<T>::max()} + 1 : M;
+    int64_t result = ForwardDiff<T, M>(last_value, new_value);
+    if (!AheadOrAt<T, M>(new_value, last_value)) {
+      result -= kBackwardAdjustment;
+    }
+    return result;
+  }
+
+  int64_t last_unwrapped_ = 0;
+  absl::optional<T> last_value_;
+};
+
+using RtpTimestampUnwrapper = SeqNumUnwrapper<uint32_t>;
+using RtpSequenceNumberUnwrapper = SeqNumUnwrapper<uint16_t>;
+
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UNWRAPPER_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/sequence_number_unwrapper_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/sequence_number_unwrapper_unittest.cc
new file mode 100644
index 0000000000..fcd903bab4
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sequence_number_unwrapper_unittest.cc
@@ -0,0 +1,146 @@
+/*
+ *  Copyright (c) 2022 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 "rtc_base/numerics/sequence_number_unwrapper.h"
+
+#include <cstdint>
+
+#include "test/gtest.h"
+
+namespace webrtc {
+
+TEST(SeqNumUnwrapper, PreserveStartValue) {
+  SeqNumUnwrapper<uint8_t> unwrapper;
+  EXPECT_EQ(123, unwrapper.Unwrap(123));
+}
+
+TEST(SeqNumUnwrapper, ForwardWrap) {
+  SeqNumUnwrapper<uint8_t> unwrapper;
+  EXPECT_EQ(255, unwrapper.Unwrap(255));
+  EXPECT_EQ(256, unwrapper.Unwrap(0));
+}
+
+TEST(SeqNumUnwrapper, ForwardWrapWithDivisor) {
+  SeqNumUnwrapper<uint8_t, 33> unwrapper;
+  EXPECT_EQ(30, unwrapper.Unwrap(30));
+  EXPECT_EQ(36, unwrapper.Unwrap(3));
+}
+
+TEST(SeqNumUnwrapper, BackWardWrap) {
+  SeqNumUnwrapper<uint8_t> unwrapper;
+  EXPECT_EQ(0, unwrapper.Unwrap(0));
+  EXPECT_EQ(-2, unwrapper.Unwrap(254));
+}
+
+TEST(SeqNumUnwrapper, BackWardWrapWithDivisor) {
+  SeqNumUnwrapper<uint8_t, 33> unwrapper;
+  EXPECT_EQ(0, unwrapper.Unwrap(0));
+  EXPECT_EQ(-2, unwrapper.Unwrap(31));
+}
+
+TEST(SeqNumUnwrapper, Unwrap) {
+  SeqNumUnwrapper<uint16_t> unwrapper;
+  const uint16_t kMax = std::numeric_limits<uint16_t>::max();
+  const uint16_t kMaxDist = kMax / 2 + 1;
+
+  EXPECT_EQ(0, unwrapper.Unwrap(0));
+  EXPECT_EQ(kMaxDist, unwrapper.Unwrap(kMaxDist));
+  EXPECT_EQ(0, unwrapper.Unwrap(0));
+
+  EXPECT_EQ(kMaxDist, unwrapper.Unwrap(kMaxDist));
+  EXPECT_EQ(kMax, unwrapper.Unwrap(kMax));
+  EXPECT_EQ(kMax + 1, unwrapper.Unwrap(0));
+  EXPECT_EQ(kMax, unwrapper.Unwrap(kMax));
+  EXPECT_EQ(kMaxDist, unwrapper.Unwrap(kMaxDist));
+  EXPECT_EQ(0, unwrapper.Unwrap(0));
+}
+
+TEST(SeqNumUnwrapper, UnwrapOddDivisor) {
+  SeqNumUnwrapper<uint8_t, 11> unwrapper;
+
+  EXPECT_EQ(10, unwrapper.Unwrap(10));
+  EXPECT_EQ(11, unwrapper.Unwrap(0));
+  EXPECT_EQ(16, unwrapper.Unwrap(5));
+  EXPECT_EQ(21, unwrapper.Unwrap(10));
+  EXPECT_EQ(22, unwrapper.Unwrap(0));
+  EXPECT_EQ(17, unwrapper.Unwrap(6));
+  EXPECT_EQ(12, unwrapper.Unwrap(1));
+  EXPECT_EQ(7, unwrapper.Unwrap(7));
+  EXPECT_EQ(2, unwrapper.Unwrap(2));
+  EXPECT_EQ(0, unwrapper.Unwrap(0));
+}
+
+TEST(SeqNumUnwrapper, ManyForwardWraps) {
+  const int kLargeNumber = 4711;
+  const int kMaxStep = kLargeNumber / 2;
+  const int kNumWraps = 100;
+  SeqNumUnwrapper<uint16_t, kLargeNumber> unwrapper;
+
+  uint16_t next_unwrap = 0;
+  int64_t expected = 0;
+  for (int i = 0; i < kNumWraps * 2 + 1; ++i) {
+    EXPECT_EQ(expected, unwrapper.Unwrap(next_unwrap));
+    expected += kMaxStep;
+    next_unwrap = (next_unwrap + kMaxStep) % kLargeNumber;
+  }
+}
+
+TEST(SeqNumUnwrapper, ManyBackwardWraps) {
+  const int kLargeNumber = 4711;
+  const int kMaxStep = kLargeNumber / 2;
+  const int kNumWraps = 100;
+  SeqNumUnwrapper<uint16_t, kLargeNumber> unwrapper;
+
+  uint16_t next_unwrap = 0;
+  int64_t expected = 0;
+  for (uint16_t i = 0; i < kNumWraps * 2 + 1; ++i) {
+    EXPECT_EQ(expected, unwrapper.Unwrap(next_unwrap));
+    expected -= kMaxStep;
+    next_unwrap = (next_unwrap + kMaxStep + 1) % kLargeNumber;
+  }
+}
+
+TEST(SeqNumUnwrapper, Reset) {
+  const uint16_t kMax = std::numeric_limits<uint16_t>::max();
+  const uint16_t kMaxStep = kMax / 2;
+  SeqNumUnwrapper<uint16_t> unwrapper;
+  EXPECT_EQ(10, unwrapper.Unwrap(10));
+  EXPECT_EQ(kMaxStep + 10, unwrapper.Unwrap(kMaxStep + 10));
+
+  EXPECT_EQ(kMax + 3, unwrapper.PeekUnwrap(2));
+  unwrapper.Reset();
+  // After Reset() the range is reset back to the start.
+  EXPECT_EQ(2, unwrapper.PeekUnwrap(2));
+}
+
+TEST(SeqNumUnwrapper, PeekUnwrap) {
+  const uint16_t kMax = std::numeric_limits<uint16_t>::max();
+  const uint16_t kMaxStep = kMax / 2;
+  const uint16_t kMaxDist = kMaxStep + 1;
+  SeqNumUnwrapper<uint16_t> unwrapper;
+  // No previous unwraps, so PeekUnwrap(x) == x.
+  EXPECT_EQ(10, unwrapper.PeekUnwrap(10));
+  EXPECT_EQ(kMaxDist + 10, unwrapper.PeekUnwrap(kMaxDist + 10));
+
+  EXPECT_EQ(10, unwrapper.Unwrap(10));
+  EXPECT_EQ(12, unwrapper.PeekUnwrap(12));
+  // State should not have updated, so kMaxDist + 12 should be negative.
+  EXPECT_EQ(-kMaxDist + 12, unwrapper.Unwrap(kMaxDist + 12));
+
+  // Test PeekUnwrap after around.
+  unwrapper.Reset();
+  EXPECT_EQ(kMaxStep, unwrapper.Unwrap(kMaxStep));
+  EXPECT_EQ(2 * kMaxStep, unwrapper.Unwrap(2 * kMaxStep));
+  EXPECT_EQ(kMax + 1, unwrapper.PeekUnwrap(0));
+  // Wrap back to last range.
+  EXPECT_EQ(kMax - 3, unwrapper.PeekUnwrap(kMax - 3));
+}
+
+}  // namespace webrtc
diff --git a/third_party/libwebrtc/rtc_base/numerics/sequence_number_util.h b/third_party/libwebrtc/rtc_base/numerics/sequence_number_util.h
new file mode 100644
index 0000000000..702b82fa2b
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sequence_number_util.h
@@ -0,0 +1,85 @@
+/*
+ *  Copyright (c) 2016 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_SEQUENCE_NUMBER_UTIL_H_
+#define RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UTIL_H_
+
+#include <stdint.h>
+
+#include <limits>
+#include <type_traits>
+
+#include "rtc_base/numerics/mod_ops.h"
+
+namespace webrtc {
+
+// Test if the sequence number `a` is ahead or at sequence number `b`.
+//
+// If `M` is an even number and the two sequence numbers are at max distance
+// from each other, then the sequence number with the highest value is
+// considered to be ahead.
+template <typename T, T M>
+inline typename std::enable_if<(M > 0), bool>::type AheadOrAt(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  const T maxDist = M / 2;
+  if (!(M & 1) && MinDiff<T, M>(a, b) == maxDist)
+    return b < a;
+  return ForwardDiff<T, M>(b, a) <= maxDist;
+}
+
+template <typename T, T M>
+inline typename std::enable_if<(M == 0), bool>::type AheadOrAt(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  const T maxDist = std::numeric_limits<T>::max() / 2 + T(1);
+  if (a - b == maxDist)
+    return b < a;
+  return ForwardDiff(b, a) < maxDist;
+}
+
+template <typename T>
+inline bool AheadOrAt(T a, T b) {
+  return AheadOrAt<T, 0>(a, b);
+}
+
+// Test if the sequence number `a` is ahead of sequence number `b`.
+//
+// If `M` is an even number and the two sequence numbers are at max distance
+// from each other, then the sequence number with the highest value is
+// considered to be ahead.
+template <typename T, T M = 0>
+inline bool AheadOf(T a, T b) {
+  static_assert(std::is_unsigned<T>::value,
+                "Type must be an unsigned integer.");
+  return a != b && AheadOrAt<T, M>(a, b);
+}
+
+// Comparator used to compare sequence numbers in a continuous fashion.
+//
+// WARNING! If used to sort sequence numbers of length M then the interval
+//          covered by the sequence numbers may not be larger than floor(M/2).
+template <typename T, T M = 0>
+struct AscendingSeqNumComp {
+  bool operator()(T a, T b) const { return AheadOf<T, M>(a, b); }
+};
+
+// Comparator used to compare sequence numbers in a continuous fashion.
+//
+// WARNING! If used to sort sequence numbers of length M then the interval
+//          covered by the sequence numbers may not be larger than floor(M/2).
+template <typename T, T M = 0>
+struct DescendingSeqNumComp {
+  bool operator()(T a, T b) const { return AheadOf<T, M>(b, a); }
+};
+
+}  // namespace webrtc
+
+#endif  // RTC_BASE_NUMERICS_SEQUENCE_NUMBER_UTIL_H_
diff --git a/third_party/libwebrtc/rtc_base/numerics/sequence_number_util_unittest.cc b/third_party/libwebrtc/rtc_base/numerics/sequence_number_util_unittest.cc
new file mode 100644
index 0000000000..d44127bfa5
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/numerics/sequence_number_util_unittest.cc
@@ -0,0 +1,215 @@
+/*
+ *  Copyright (c) 2016 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 "rtc_base/numerics/sequence_number_util.h"
+
+#include <cstdint>
+#include <iterator>
+#include <set>
+
+#include "test/gtest.h"
+
+namespace webrtc {
+class TestSeqNumUtil : public ::testing::Test {
+ protected:
+  // Can't use std::numeric_limits<unsigned long>::max() since
+  // MSVC doesn't support constexpr.
+  static const unsigned long ulmax = ~0ul;  // NOLINT
+};
+
+TEST_F(TestSeqNumUtil, AheadOrAt) {
+  uint8_t x = 0;
+  uint8_t y = 0;
+  ASSERT_TRUE(AheadOrAt(x, y));
+  ++x;
+  ASSERT_TRUE(AheadOrAt(x, y));
+  ASSERT_FALSE(AheadOrAt(y, x));
+  for (int i = 0; i < 256; ++i) {
+    ASSERT_TRUE(AheadOrAt(x, y));
+    ++x;
+    ++y;
+  }
+
+  x = 128;
+  y = 0;
+  ASSERT_TRUE(AheadOrAt(x, y));
+  ASSERT_FALSE(AheadOrAt(y, x));
+
+  x = 129;
+  ASSERT_FALSE(AheadOrAt(x, y));
+  ASSERT_TRUE(AheadOrAt(y, x));
+  ASSERT_TRUE(AheadOrAt<uint16_t>(x, y));
+  ASSERT_FALSE(AheadOrAt<uint16_t>(y, x));
+}
+
+TEST_F(TestSeqNumUtil, AheadOrAtWithDivisor) {
+  ASSERT_TRUE((AheadOrAt<uint8_t, 11>(5, 0)));
+  ASSERT_FALSE((AheadOrAt<uint8_t, 11>(6, 0)));
+  ASSERT_FALSE((AheadOrAt<uint8_t, 11>(0, 5)));
+  ASSERT_TRUE((AheadOrAt<uint8_t, 11>(0, 6)));
+
+  ASSERT_TRUE((AheadOrAt<uint8_t, 10>(5, 0)));
+  ASSERT_FALSE((AheadOrAt<uint8_t, 10>(6, 0)));
+  ASSERT_FALSE((AheadOrAt<uint8_t, 10>(0, 5)));
+  ASSERT_TRUE((AheadOrAt<uint8_t, 10>(0, 6)));
+
+  const uint8_t D = 211;
+  uint8_t x = 0;
+  for (int i = 0; i < D; ++i) {
+    uint8_t next_x = Add<D>(x, 1);
+    ASSERT_TRUE((AheadOrAt<uint8_t, D>(i, i)));
+    ASSERT_TRUE((AheadOrAt<uint8_t, D>(next_x, i)));
+    ASSERT_FALSE((AheadOrAt<uint8_t, D>(i, next_x)));
+    x = next_x;
+  }
+}
+
+TEST_F(TestSeqNumUtil, AheadOf) {
+  uint8_t x = 0;
+  uint8_t y = 0;
+  ASSERT_FALSE(AheadOf(x, y));
+  ++x;
+  ASSERT_TRUE(AheadOf(x, y));
+  ASSERT_FALSE(AheadOf(y, x));
+  for (int i = 0; i < 256; ++i) {
+    ASSERT_TRUE(AheadOf(x, y));
+    ++x;
+    ++y;
+  }
+
+  x = 128;
+  y = 0;
+  for (int i = 0; i < 128; ++i) {
+    ASSERT_TRUE(AheadOf(x, y));
+    ASSERT_FALSE(AheadOf(y, x));
+    x++;
+    y++;
+  }
+
+  for (int i = 0; i < 128; ++i) {
+    ASSERT_FALSE(AheadOf(x, y));
+    ASSERT_TRUE(AheadOf(y, x));
+    x++;
+    y++;
+  }
+
+  x = 129;
+  y = 0;
+  ASSERT_FALSE(AheadOf(x, y));
+  ASSERT_TRUE(AheadOf(y, x));
+  ASSERT_TRUE(AheadOf<uint16_t>(x, y));
+  ASSERT_FALSE(AheadOf<uint16_t>(y, x));
+}
+
+TEST_F(TestSeqNumUtil, AheadOfWithDivisor) {
+  ASSERT_TRUE((AheadOf<uint8_t, 11>(5, 0)));
+  ASSERT_FALSE((AheadOf<uint8_t, 11>(6, 0)));
+  ASSERT_FALSE((AheadOf<uint8_t, 11>(0, 5)));
+  ASSERT_TRUE((AheadOf<uint8_t, 11>(0, 6)));
+
+  ASSERT_TRUE((AheadOf<uint8_t, 10>(5, 0)));
+  ASSERT_FALSE((AheadOf<uint8_t, 10>(6, 0)));
+  ASSERT_FALSE((AheadOf<uint8_t, 10>(0, 5)));
+  ASSERT_TRUE((AheadOf<uint8_t, 10>(0, 6)));
+
+  const uint8_t D = 211;
+  uint8_t x = 0;
+  for (int i = 0; i < D; ++i) {
+    uint8_t next_x = Add<D>(x, 1);
+    ASSERT_FALSE((AheadOf<uint8_t, D>(i, i)));
+    ASSERT_TRUE((AheadOf<uint8_t, D>(next_x, i)));
+    ASSERT_FALSE((AheadOf<uint8_t, D>(i, next_x)));
+    x = next_x;
+  }
+}
+
+TEST_F(TestSeqNumUtil, ForwardDiffWithDivisor) {
+  const uint8_t kDivisor = 211;
+
+  for (uint8_t i = 0; i < kDivisor - 1; ++i) {
+    ASSERT_EQ(0, (ForwardDiff<uint8_t, kDivisor>(i, i)));
+    ASSERT_EQ(1, (ForwardDiff<uint8_t, kDivisor>(i, i + 1)));
+    ASSERT_EQ(kDivisor - 1, (ForwardDiff<uint8_t, kDivisor>(i + 1, i)));
+  }
+
+  for (uint8_t i = 1; i < kDivisor; ++i) {
+    ASSERT_EQ(i, (ForwardDiff<uint8_t, kDivisor>(0, i)));
+    ASSERT_EQ(kDivisor - i, (ForwardDiff<uint8_t, kDivisor>(i, 0)));
+  }
+}
+
+TEST_F(TestSeqNumUtil, ReverseDiffWithDivisor) {
+  const uint8_t kDivisor = 241;
+
+  for (uint8_t i = 0; i < kDivisor - 1; ++i) {
+    ASSERT_EQ(0, (ReverseDiff<uint8_t, kDivisor>(i, i)));
+    ASSERT_EQ(kDivisor - 1, (ReverseDiff<uint8_t, kDivisor>(i, i + 1)));
+    ASSERT_EQ(1, (ReverseDiff<uint8_t, kDivisor>(i + 1, i)));
+  }
+
+  for (uint8_t i = 1; i < kDivisor; ++i) {
+    ASSERT_EQ(kDivisor - i, (ReverseDiff<uint8_t, kDivisor>(0, i)));
+    ASSERT_EQ(i, (ReverseDiff<uint8_t, kDivisor>(i, 0)));
+  }
+}
+
+TEST_F(TestSeqNumUtil, SeqNumComparator) {
+  std::set<uint8_t, AscendingSeqNumComp<uint8_t>> seq_nums_asc;
+  std::set<uint8_t, DescendingSeqNumComp<uint8_t>> seq_nums_desc;
+
+  uint8_t x = 0;
+  for (int i = 0; i < 128; ++i) {
+    seq_nums_asc.insert(x);
+    seq_nums_desc.insert(x);
+    ASSERT_EQ(x, *seq_nums_asc.begin());
+    ASSERT_EQ(x, *seq_nums_desc.rbegin());
+    ++x;
+  }
+
+  seq_nums_asc.clear();
+  seq_nums_desc.clear();
+  x = 199;
+  for (int i = 0; i < 128; ++i) {
+    seq_nums_asc.insert(x);
+    seq_nums_desc.insert(x);
+    ASSERT_EQ(x, *seq_nums_asc.begin());
+    ASSERT_EQ(x, *seq_nums_desc.rbegin());
+    ++x;
+  }
+}
+
+TEST_F(TestSeqNumUtil, SeqNumComparatorWithDivisor) {
+  const uint8_t D = 223;
+
+  std::set<uint8_t, AscendingSeqNumComp<uint8_t, D>> seq_nums_asc;
+  std::set<uint8_t, DescendingSeqNumComp<uint8_t, D>> seq_nums_desc;
+
+  uint8_t x = 0;
+  for (int i = 0; i < D / 2; ++i) {
+    seq_nums_asc.insert(x);
+    seq_nums_desc.insert(x);
+    ASSERT_EQ(x, *seq_nums_asc.begin());
+    ASSERT_EQ(x, *seq_nums_desc.rbegin());
+    x = Add<D>(x, 1);
+  }
+
+  seq_nums_asc.clear();
+  seq_nums_desc.clear();
+  x = 200;
+  for (int i = 0; i < D / 2; ++i) {
+    seq_nums_asc.insert(x);
+    seq_nums_desc.insert(x);
+    ASSERT_EQ(x, *seq_nums_asc.begin());
+    ASSERT_EQ(x, *seq_nums_desc.rbegin());
+    x = Add<D>(x, 1);
+  }
+}
+
+}  // namespace webrtc