Update to current webrtc library

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

webrtc/api/units/data_rate.cc

@@ -0,0 +1,34 @@
+/*
+ *  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 "api/units/data_rate.h"
+
+#include "api/array_view.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+
+std::string ToString(DataRate value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf bps";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf bps";
+  } else {
+    if (value.bps() == 0 || value.bps() % 1000 != 0) {
+      sb << value.bps() << " bps";
+    } else {
+      sb << value.kbps() << " kbps";
+    }
+  }
+  return sb.str();
+}
+}  // namespace webrtc

webrtc/api/units/data_rate.h

@@ -0,0 +1,155 @@
+/*
+ *  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_DATA_RATE_H_
+#define API_UNITS_DATA_RATE_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <limits>
+#include <string>
+#include <type_traits>
+
+#include "api/units/data_size.h"
+#include "api/units/frequency.h"
+#include "api/units/time_delta.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/units/unit_base.h"
+
+namespace webrtc {
+// DataRate is a class that represents a given data rate. This can be used to
+// represent bandwidth, encoding bitrate, etc. The internal storage is bits per
+// second (bps).
+class DataRate final : public rtc_units_impl::RelativeUnit<DataRate> {
+ public:
+  template <typename T>
+  static constexpr DataRate BitsPerSec(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+  template <typename T>
+  static constexpr DataRate BytesPerSec(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(8, value);
+  }
+  template <typename T>
+  static constexpr DataRate KilobitsPerSec(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1000, value);
+  }
+  static constexpr DataRate Infinity() { return PlusInfinity(); }
+
+  DataRate() = delete;
+
+  template <typename T = int64_t>
+  constexpr T bps() const {
+    return ToValue<T>();
+  }
+  template <typename T = int64_t>
+  constexpr T bytes_per_sec() const {
+    return ToFraction<8, T>();
+  }
+  template <typename T = int64_t>
+  constexpr T kbps() const {
+    return ToFraction<1000, T>();
+  }
+  constexpr int64_t bps_or(int64_t fallback_value) const {
+    return ToValueOr(fallback_value);
+  }
+  constexpr int64_t kbps_or(int64_t fallback_value) const {
+    return ToFractionOr<1000>(fallback_value);
+  }
+
+ private:
+  // Bits per second used internally to simplify debugging by making the value
+  // more recognizable.
+  friend class rtc_units_impl::UnitBase<DataRate>;
+  using RelativeUnit::RelativeUnit;
+  static constexpr bool one_sided = true;
+};
+
+namespace data_rate_impl {
+inline constexpr int64_t Microbits(const DataSize& size) {
+  constexpr int64_t kMaxBeforeConversion =
+      std::numeric_limits<int64_t>::max() / 8000000;
+  RTC_DCHECK_LE(size.bytes(), kMaxBeforeConversion)
+      << "size is too large to be expressed in microbits";
+  return size.bytes() * 8000000;
+}
+
+inline constexpr int64_t MillibytePerSec(const DataRate& size) {
+  constexpr int64_t kMaxBeforeConversion =
+      std::numeric_limits<int64_t>::max() / (1000 / 8);
+  RTC_DCHECK_LE(size.bps(), kMaxBeforeConversion)
+      << "rate is too large to be expressed in microbytes per second";
+  return size.bps() * (1000 / 8);
+}
+}  // namespace data_rate_impl
+
+inline constexpr DataRate operator/(const DataSize size,
+                                    const TimeDelta duration) {
+  return DataRate::BitsPerSec(data_rate_impl::Microbits(size) / duration.us());
+}
+inline constexpr TimeDelta operator/(const DataSize size, const DataRate rate) {
+  return TimeDelta::Micros(data_rate_impl::Microbits(size) / rate.bps());
+}
+inline constexpr DataSize operator*(const DataRate rate,
+                                    const TimeDelta duration) {
+  int64_t microbits = rate.bps() * duration.us();
+  return DataSize::Bytes((microbits + 4000000) / 8000000);
+}
+inline constexpr DataSize operator*(const TimeDelta duration,
+                                    const DataRate rate) {
+  return rate * duration;
+}
+
+inline constexpr DataSize operator/(const DataRate rate,
+                                    const Frequency frequency) {
+  int64_t millihertz = frequency.millihertz<int64_t>();
+  // Note that the value is truncated here reather than rounded, potentially
+  // introducing an error of .5 bytes if rounding were expected.
+  return DataSize::Bytes(data_rate_impl::MillibytePerSec(rate) / millihertz);
+}
+inline constexpr Frequency operator/(const DataRate rate, const DataSize size) {
+  return Frequency::MilliHertz(data_rate_impl::MillibytePerSec(rate) /
+                               size.bytes());
+}
+inline constexpr DataRate operator*(const DataSize size,
+                                    const Frequency frequency) {
+  RTC_DCHECK(frequency.IsZero() ||
+             size.bytes() <= std::numeric_limits<int64_t>::max() / 8 /
+                                 frequency.millihertz<int64_t>());
+  int64_t millibits_per_second =
+      size.bytes() * 8 * frequency.millihertz<int64_t>();
+  return DataRate::BitsPerSec((millibits_per_second + 500) / 1000);
+}
+inline constexpr DataRate operator*(const Frequency frequency,
+                                    const DataSize size) {
+  return size * frequency;
+}
+
+std::string ToString(DataRate value);
+inline std::string ToLogString(DataRate 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)
+    DataRate value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+
+#endif  // API_UNITS_DATA_RATE_H_

webrtc/api/units/data_size.cc

@@ -0,0 +1,30 @@
+/*
+ *  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 "api/units/data_size.h"
+
+#include "api/array_view.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+
+std::string ToString(DataSize value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf bytes";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf bytes";
+  } else {
+    sb << value.bytes() << " bytes";
+  }
+  return sb.str();
+}
+}  // namespace webrtc

webrtc/api/units/data_size.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 API_UNITS_DATA_SIZE_H_
+#define API_UNITS_DATA_SIZE_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <string>
+#include <type_traits>
+
+#include "rtc_base/units/unit_base.h"
+
+namespace webrtc {
+// DataSize is a class represeting a count of bytes.
+class DataSize final : public rtc_units_impl::RelativeUnit<DataSize> {
+ public:
+  template <typename T>
+  static constexpr DataSize Bytes(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+  static constexpr DataSize Infinity() { return PlusInfinity(); }
+
+  DataSize() = delete;
+
+  template <typename T = int64_t>
+  constexpr T bytes() const {
+    return ToValue<T>();
+  }
+
+  constexpr int64_t bytes_or(int64_t fallback_value) const {
+    return ToValueOr(fallback_value);
+  }
+
+ private:
+  friend class rtc_units_impl::UnitBase<DataSize>;
+  using RelativeUnit::RelativeUnit;
+  static constexpr bool one_sided = true;
+};
+
+std::string ToString(DataSize value);
+inline std::string ToLogString(DataSize 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)
+    DataSize value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+
+#endif  // API_UNITS_DATA_SIZE_H_

webrtc/api/units/frequency.cc

@@ -0,0 +1,29 @@
+/*
+ *  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 "api/units/frequency.h"
+
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+std::string ToString(Frequency value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf Hz";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf Hz";
+  } else if (value.millihertz<int64_t>() % 1000 != 0) {
+    sb.AppendFormat("%.3f Hz", value.hertz<double>());
+  } else {
+    sb << value.hertz<int64_t>() << " Hz";
+  }
+  return sb.str();
+}
+}  // namespace webrtc

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_

webrtc/api/units/time_delta.cc

@@ -0,0 +1,36 @@
+/*
+ *  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 "api/units/time_delta.h"
+
+#include "api/array_view.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+
+std::string ToString(TimeDelta value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf ms";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf ms";
+  } else {
+    if (value.us() == 0 || (value.us() % 1000) != 0)
+      sb << value.us() << " us";
+    else if (value.ms() % 1000 != 0)
+      sb << value.ms() << " ms";
+    else
+      sb << value.seconds() << " s";
+  }
+  return sb.str();
+}
+
+}  // namespace webrtc

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_

webrtc/api/units/timestamp.cc

@@ -0,0 +1,34 @@
+/*
+ *  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 "api/units/timestamp.h"
+
+#include "api/array_view.h"
+#include "rtc_base/strings/string_builder.h"
+
+namespace webrtc {
+std::string ToString(Timestamp value) {
+  char buf[64];
+  rtc::SimpleStringBuilder sb(buf);
+  if (value.IsPlusInfinity()) {
+    sb << "+inf ms";
+  } else if (value.IsMinusInfinity()) {
+    sb << "-inf ms";
+  } else {
+    if (value.us() == 0 || (value.us() % 1000) != 0)
+      sb << value.us() << " us";
+    else if (value.ms() % 1000 != 0)
+      sb << value.ms() << " ms";
+    else
+      sb << value.seconds() << " s";
+  }
+  return sb.str();
+}
+}  // namespace webrtc

webrtc/api/units/timestamp.h

@@ -0,0 +1,138 @@
+/*
+ *  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_TIMESTAMP_H_
+#define API_UNITS_TIMESTAMP_H_
+
+#ifdef UNIT_TEST
+#include <ostream>  // no-presubmit-check TODO(webrtc:8982)
+#endif              // UNIT_TEST
+
+#include <string>
+#include <type_traits>
+
+#include "api/units/time_delta.h"
+#include "rtc_base/checks.h"
+
+namespace webrtc {
+// Timestamp represents the time that has passed since some unspecified epoch.
+// The epoch is assumed to be before any represented timestamps, this means that
+// negative values are not valid. The most notable feature is that the
+// difference of two Timestamps results in a TimeDelta.
+class Timestamp final : public rtc_units_impl::UnitBase<Timestamp> {
+ public:
+  template <typename T>
+  static constexpr Timestamp Seconds(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000'000, value);
+  }
+  template <typename T>
+  static constexpr Timestamp Millis(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromFraction(1'000, value);
+  }
+  template <typename T>
+  static constexpr Timestamp Micros(T value) {
+    static_assert(std::is_arithmetic<T>::value, "");
+    return FromValue(value);
+  }
+
+  Timestamp() = 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>();
+  }
+
+  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 Timestamp operator+(const TimeDelta delta) const {
+    if (IsPlusInfinity() || delta.IsPlusInfinity()) {
+      RTC_DCHECK(!IsMinusInfinity());
+      RTC_DCHECK(!delta.IsMinusInfinity());
+      return PlusInfinity();
+    } else if (IsMinusInfinity() || delta.IsMinusInfinity()) {
+      RTC_DCHECK(!IsPlusInfinity());
+      RTC_DCHECK(!delta.IsPlusInfinity());
+      return MinusInfinity();
+    }
+    return Timestamp::Micros(us() + delta.us());
+  }
+  constexpr Timestamp operator-(const TimeDelta delta) const {
+    if (IsPlusInfinity() || delta.IsMinusInfinity()) {
+      RTC_DCHECK(!IsMinusInfinity());
+      RTC_DCHECK(!delta.IsPlusInfinity());
+      return PlusInfinity();
+    } else if (IsMinusInfinity() || delta.IsPlusInfinity()) {
+      RTC_DCHECK(!IsPlusInfinity());
+      RTC_DCHECK(!delta.IsMinusInfinity());
+      return MinusInfinity();
+    }
+    return Timestamp::Micros(us() - delta.us());
+  }
+  constexpr TimeDelta operator-(const Timestamp other) const {
+    if (IsPlusInfinity() || other.IsMinusInfinity()) {
+      RTC_DCHECK(!IsMinusInfinity());
+      RTC_DCHECK(!other.IsPlusInfinity());
+      return TimeDelta::PlusInfinity();
+    } else if (IsMinusInfinity() || other.IsPlusInfinity()) {
+      RTC_DCHECK(!IsPlusInfinity());
+      RTC_DCHECK(!other.IsMinusInfinity());
+      return TimeDelta::MinusInfinity();
+    }
+    return TimeDelta::Micros(us() - other.us());
+  }
+  constexpr Timestamp& operator-=(const TimeDelta delta) {
+    *this = *this - delta;
+    return *this;
+  }
+  constexpr Timestamp& operator+=(const TimeDelta delta) {
+    *this = *this + delta;
+    return *this;
+  }
+
+ private:
+  friend class rtc_units_impl::UnitBase<Timestamp>;
+  using UnitBase::UnitBase;
+  static constexpr bool one_sided = true;
+};
+
+std::string ToString(Timestamp value);
+inline std::string ToLogString(Timestamp 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)
+    Timestamp value) {
+  return stream << ToString(value);
+}
+#endif  // UNIT_TEST
+
+}  // namespace webrtc
+
+#endif  // API_UNITS_TIMESTAMP_H_