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diff --git a/mozglue/misc/TimeStamp_windows.h b/mozglue/misc/TimeStamp_windows.h
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+++ b/mozglue/misc/TimeStamp_windows.h
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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_TimeStamp_windows_h
+#define mozilla_TimeStamp_windows_h
+
+#include "mozilla/Types.h"
+
+namespace mozilla {
+
+/**
+ * The [mt] unit:
+ *
+ * Many values are kept in ticks of the Performance Counter x 1000,
+ * further just referred as [mt], meaning milli-ticks.
+ *
+ * This is needed to preserve maximum precision of the performance frequency
+ * representation.  GetTickCount64 values in milliseconds are multiplied with
+ * frequency per second.  Therefore we need to multiply QPC value by 1000 to
+ * have the same units to allow simple arithmentic with both QPC and GTC.
+ */
+#define ms2mt(x) ((x)*mozilla::GetQueryPerformanceFrequencyPerSec())
+#define mt2ms(x) ((x) / mozilla::GetQueryPerformanceFrequencyPerSec())
+#define mt2ms_f(x) (double(x) / mozilla::GetQueryPerformanceFrequencyPerSec())
+
+MFBT_API uint64_t GetQueryPerformanceFrequencyPerSec();
+
+class TimeStamp;
+class TimeStampValue;
+
+TimeStampValue NowInternal(bool aHighResolution);
+
+class TimeStampValue {
+  friend TimeStampValue NowInternal(bool);
+  friend bool IsCanonicalTimeStamp(TimeStampValue);
+  friend struct IPC::ParamTraits<mozilla::TimeStampValue>;
+  friend class TimeStamp;
+
+  // Both QPC and GTC are kept in [mt] units.
+  uint64_t mGTC;
+  uint64_t mQPC;
+
+  bool mIsNull;
+  bool mHasQPC;
+
+  MFBT_API TimeStampValue(uint64_t aGTC, uint64_t aQPC, bool aHasQPC);
+
+  MFBT_API uint64_t CheckQPC(const TimeStampValue& aOther) const;
+
+  // This struct is used to allow doing TimeStampValue a = 0 and similar
+  struct _SomethingVeryRandomHere;
+  constexpr MOZ_IMPLICIT TimeStampValue(_SomethingVeryRandomHere* aNullValue)
+      : mGTC(0), mQPC(0), mIsNull(true), mHasQPC(false) {}
+
+ public:
+  MFBT_API uint64_t operator-(const TimeStampValue& aOther) const;
+
+  TimeStampValue operator+(const int64_t aOther) const {
+    return TimeStampValue(mGTC + aOther, mQPC + aOther, mHasQPC);
+  }
+  TimeStampValue operator-(const int64_t aOther) const {
+    return TimeStampValue(mGTC - aOther, mQPC - aOther, mHasQPC);
+  }
+  MFBT_API TimeStampValue& operator+=(const int64_t aOther);
+  MFBT_API TimeStampValue& operator-=(const int64_t aOther);
+
+  bool operator<(const TimeStampValue& aOther) const {
+    return int64_t(*this - aOther) < 0;
+  }
+  bool operator>(const TimeStampValue& aOther) const {
+    return int64_t(*this - aOther) > 0;
+  }
+  bool operator<=(const TimeStampValue& aOther) const {
+    return int64_t(*this - aOther) <= 0;
+  }
+  bool operator>=(const TimeStampValue& aOther) const {
+    return int64_t(*this - aOther) >= 0;
+  }
+  bool operator==(const TimeStampValue& aOther) const {
+    return int64_t(*this - aOther) == 0;
+  }
+  bool operator!=(const TimeStampValue& aOther) const {
+    return int64_t(*this - aOther) != 0;
+  }
+  bool IsNull() const { return mIsNull; }
+};
+
+}  // namespace mozilla
+
+#endif /* mozilla_TimeStamp_h */