Change QuicWallTime to have microsecond granularity.

net/quic/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/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::FromUNIXSeconds(base::Time::Now().ToTimeT());
+  return QuicWallTime::FromUNIXMicroseconds(base::Time::Now().ToJavaTime() * 1000);
 }
 
 }  // namespace net