Use {To/From}JavaTime for policy timestamps

chrome/browser/chromeos/policy/device_status_collector.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 "chrome/browser/chromeos/policy/device_status_collector.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
@@ skipping 88 matching lines @@
 const char kCPUTempFilePattern[] = "temp*_input";
 
 // Determine the day key (milliseconds since epoch for corresponding day in UTC)
 // for a given |timestamp|.
 int64_t TimestampToDayKey(Time timestamp) {
   Time::Exploded exploded;
   timestamp.LocalMidnight().LocalExplode(&exploded);
   Time out_time;
   bool conversion_success = Time::FromUTCExploded(exploded, &out_time);
   DCHECK(conversion_success);
-  return (out_time - Time::UnixEpoch()).InMilliseconds();
+  return out_time.ToJavaTime();
 }
 
 // Helper function (invoked via blocking pool) to fetch information about
 // mounted disks.
 std::vector<em::VolumeInfo> GetVolumeInfo(
     const std::vector<std::string>& mount_points) {
   std::vector<em::VolumeInfo> result;
   for (const std::string& mount_point : mount_points) {
     base::FilePath mount_path(mount_point);
 
@@ skipping 1148 matching lines @@
 
 void DeviceStatusCollector::OnOSVersion(const std::string& version) {
   os_version_ = version;
 }
 
 void DeviceStatusCollector::OnOSFirmware(const std::string& version) {
   firmware_version_ = version;
 }
 
 }  // namespace policy