GOAWAY open QUIC sessions if clock skew is detected

net/quic/chromium/quic_clock_skew_detector.cc

+// 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.
+
+#include "net/quic/chromium/quic_clock_skew_detector.h"
+
+#include "base/metrics/histogram_macros.h"
+
+namespace net {
+
+QuicClockSkewDetector::QuicClockSkewDetector(base::TimeTicks ticks_time,
+                                             base::Time wall_time)
+    : last_ticks_time_(ticks_time), last_wall_time_(wall_time) {}
+
+bool QuicClockSkewDetector::ClockSkewDetected(base::TimeTicks ticks_now,
+                                              base::Time wall_now) {
+  base::TimeDelta ticks_delta = ticks_now - last_ticks_time_;
+  base::TimeDelta wall_delta = wall_now - last_wall_time_;
+  base::TimeDelta offset = wall_delta - ticks_delta;
+  last_wall_time_ = wall_now;
+  last_ticks_time_ = ticks_now;
+
+  UMA_HISTOGRAM_TIMES(
+      "Net.QuicClock.SkewOffset",
+      base::TimeDelta::FromMicroseconds(offset.InMicroseconds()));
+
+  if (offset < base::TimeDelta::FromSeconds(1))
+    return false;
+
+  return true;
+}
+
+}  // namespace net