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diff --git a/chromium/net/third_party/quiche/src/quic/core/quic_clock.h b/chromium/net/third_party/quiche/src/quic/core/quic_clock.h
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+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef QUICHE_QUIC_CORE_QUIC_CLOCK_H_
+#define QUICHE_QUIC_CORE_QUIC_CLOCK_H_
+
+#include "net/third_party/quiche/src/quic/core/quic_time.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
+
+/* API_DESCRIPTION
+ QuicClock is used by QUIC core to get current time. Its instance is created by
+ applications and passed into QuicDispatcher and QuicConnectionHelperInterface.
+ API-DESCRIPTION */
+
+namespace quic {
+
+// Interface for retrieving the current time.
+class QUIC_EXPORT_PRIVATE QuicClock {
+ public:
+  QuicClock();
+  virtual ~QuicClock();
+
+  QuicClock(const QuicClock&) = delete;
+  QuicClock& operator=(const QuicClock&) = delete;
+
+  // Compute the offset between this clock with the Unix Epoch clock.
+  // Return the calibrated offset between WallNow() and Now(), in the form of
+  // (wallnow_in_us - now_in_us).
+  // The return value can be used by SetCalibrationOffset() to actually
+  // calibrate the clock, or all instances of this clock type.
+  QuicTime::Delta ComputeCalibrationOffset() const;
+
+  // Calibrate this clock. A calibrated clock guarantees that the
+  // ConvertWallTimeToQuicTime() function always return the same result for the
+  // same walltime.
+  // Should not be called more than once for each QuicClock.
+  void SetCalibrationOffset(QuicTime::Delta offset);
+
+  // Returns the approximate current time as a QuicTime object.
+  virtual QuicTime ApproximateNow() const = 0;
+
+  // Returns the current time as a QuicTime object.
+  // Note: this use significant resources please use only if needed.
+  virtual QuicTime Now() const = 0;
+
+  // WallNow returns the current wall-time - a time that is consistent across
+  // different clocks.
+  virtual QuicWallTime WallNow() const = 0;
+
+  // Converts |walltime| to a QuicTime relative to this clock's epoch.
+  virtual QuicTime ConvertWallTimeToQuicTime(
+      const QuicWallTime& walltime) const;
+
+ protected:
+  // Creates a new QuicTime using |time_us| as the internal value.
+  QuicTime CreateTimeFromMicroseconds(uint64_t time_us) const {
+    return QuicTime(time_us);
+  }
+
+ private:
+  // True if |calibration_offset_| is valid.
+  bool is_calibrated_;
+  // If |is_calibrated_|, |calibration_offset_| is the (fixed) offset between
+  // the Unix Epoch clock and this clock.
+  // In other words, the offset between WallNow() and Now().
+  QuicTime::Delta calibration_offset_;
+};
+
+}  // namespace quic
+
+#endif  // QUICHE_QUIC_CORE_QUIC_CLOCK_H_