Update to current webrtc library

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

webrtc/api/units/time_delta.h

@@ -0,0 +1,105 @@
+/*
+ *  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 API_UNITS_TIME_DELTA_H_
+#define API_UNITS_TIME_DELTA_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <cstdlib>
+#include <string>
+#include <type_traits>
+
+#include "rtc_base/units/unit_base.h"
+
+namespace webrtc {
+
+// TimeDelta represents the difference between two timestamps. Commonly this can
+// be a duration. However since two Timestamps are not guaranteed to have the
+// same epoch (they might come from different computers, making exact
+// synchronisation infeasible), the duration covered by a TimeDelta can be
+// undefined. To simplify usage, it can be constructed and converted to
+// different units, specifically seconds (s), milliseconds (ms) and
+// microseconds (us).
+class TimeDelta final : public rtc_units_impl::RelativeUnit<TimeDelta> {
+ public:
+  template <typename T>
+  static constexpr TimeDelta Seconds(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000'000, value);
+  }
+  template <typename T>
+  static constexpr TimeDelta Millis(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000, value);
+  }
+  template <typename T>
+  static constexpr TimeDelta Micros(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+
+  TimeDelta() = delete;
+
+  template <typename T = int64_t>
+  constexpr T seconds() const {
+    return ToFraction<1000000, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T ms() const {
+    return ToFraction<1000, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T us() const {
+    return ToValue<T>();
+  }
+  template <typename T = int64_t>
+  constexpr T ns() const {
+    return ToMultiple<1000, T>();
+  }
+
+  constexpr int64_t seconds_or(int64_t fallback_value) const {
+    return ToFractionOr<1000000>(fallback_value);
+  }
+  constexpr int64_t ms_or(int64_t fallback_value) const {
+    return ToFractionOr<1000>(fallback_value);
+  }
+  constexpr int64_t us_or(int64_t fallback_value) const {
+    return ToValueOr(fallback_value);
+  }
+
+  constexpr TimeDelta Abs() const {
+    return us() < 0 ? TimeDelta::Micros(-us()) : *this;
+  }
+
+ private:
+  friend class rtc_units_impl::UnitBase<TimeDelta>;
+  using RelativeUnit::RelativeUnit;
+  static constexpr bool one_sided = false;
+};
+
+std::string ToString(TimeDelta value);
+inline std::string ToLogString(TimeDelta 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)
+    TimeDelta value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+
+#endif  // API_UNITS_TIME_DELTA_H_