Move QuicClock to quic/platform/

net/quic/core/quic_clock.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/core/quic_clock.h"
-
-#include "base/time/time.h"
-
-namespace net {
-
-QuicClock::QuicClock() {}
-
-QuicClock::~QuicClock() {}
-
-QuicTime QuicClock::ApproximateNow() const {
-  // At the moment, Chrome does not have a distinct notion of ApproximateNow().
-  // We should consider implementing this using MessageLoop::recent_time_.
-  return Now();
-}
-
-QuicTime QuicClock::Now() const {
-  return QuicTime(base::TimeTicks::Now());
-}
-
-QuicWallTime QuicClock::WallNow() const {
-  return QuicWallTime::FromUNIXMicroseconds(base::Time::Now().ToJavaTime() *
-                                            1000);
-}
-
-QuicTime QuicClock::ConvertWallTimeToQuicTime(
-    const QuicWallTime& walltime) const {
-  //     ..........................
-  //     |            |           |
-  // unix epoch   |walltime|   WallNow()
-  //     ..........................
-  //            |     |           |
-  //     clock epoch  |         Now()
-  //               result
-  //
-  // result = Now() - (WallNow() - walltime)
-  return Now() - QuicTime::Delta::FromMicroseconds(
-                     WallNow()
-                         .Subtract(QuicTime::Delta::FromMicroseconds(
-                             walltime.ToUNIXMicroseconds()))
-                         .ToUNIXMicroseconds());
-}
-
-}  // namespace net