Update to current webrtc library

This is from the upstream library commit id
3326535126e435f1ba647885ce43a8f0f3d317eb, corresponding to Chromium
88.0.4290.1.

webrtc/api/units/frequency.h

@@ -0,0 +1,101 @@
+/*
+ *  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_UNITS_FREQUENCY_H_
+#define API_UNITS_FREQUENCY_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <cstdlib>
+#include <limits>
+#include <string>
+#include <type_traits>
+
+#include "api/units/time_delta.h"
+#include "rtc_base/units/unit_base.h"
+
+namespace webrtc {
+
+class Frequency final : public rtc_units_impl::RelativeUnit<Frequency> {
+ public:
+  template <typename T>
+  static constexpr Frequency MilliHertz(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+  template <typename T>
+  static constexpr Frequency Hertz(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000, value);
+  }
+  template <typename T>
+  static constexpr Frequency KiloHertz(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000'000, value);
+  }
+
+  Frequency() = delete;
+
+  template <typename T = int64_t>
+  constexpr T hertz() const {
+    return ToFraction<1000, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T millihertz() const {
+    return ToValue<T>();
+  }
+
+ private:
+  friend class rtc_units_impl::UnitBase<Frequency>;
+  using RelativeUnit::RelativeUnit;
+  static constexpr bool one_sided = true;
+};
+
+inline constexpr Frequency operator/(int64_t nominator,
+                                     const TimeDelta& interval) {
+  constexpr int64_t kKiloPerMicro = 1000 * 1000000;
+  RTC_DCHECK_LE(nominator, std::numeric_limits<int64_t>::max() / kKiloPerMicro);
+  RTC_CHECK(interval.IsFinite());
+  RTC_CHECK(!interval.IsZero());
+  return Frequency::MilliHertz(nominator * kKiloPerMicro / interval.us());
+}
+
+inline constexpr TimeDelta operator/(int64_t nominator,
+                                     const Frequency& frequency) {
+  constexpr int64_t kMegaPerMilli = 1000000 * 1000;
+  RTC_DCHECK_LE(nominator, std::numeric_limits<int64_t>::max() / kMegaPerMilli);
+  RTC_CHECK(frequency.IsFinite());
+  RTC_CHECK(!frequency.IsZero());
+  return TimeDelta::Micros(nominator * kMegaPerMilli / frequency.millihertz());
+}
+
+inline constexpr double operator*(Frequency frequency, TimeDelta time_delta) {
+  return frequency.hertz<double>() * time_delta.seconds<double>();
+}
+inline constexpr double operator*(TimeDelta time_delta, Frequency frequency) {
+  return frequency * time_delta;
+}
+
+std::string ToString(Frequency value);
+inline std::string ToLogString(Frequency value) {
+  return ToString(value);
+}
+
+#ifdef UNIT_TEST
+inline std::ostream& operator<<(  // no-presubmit-check TODO(webrtc:8982)
+    std::ostream& stream,         // no-presubmit-check TODO(webrtc:8982)
+    Frequency value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+#endif  // API_UNITS_FREQUENCY_H_