Use {To/From}JavaTime for policy timestamps

components/policy/core/common/cloud/cloud_policy_client.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 "components/policy/core/common/cloud/cloud_policy_client.h"
 
 #include <utility>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 219 matching lines @@
     fetch_request->set_signature_type(em::PolicyFetchRequest::SHA1_RSA);
     if (public_key_version_valid_)
       fetch_request->set_public_key_version(public_key_version_);
 
     fetch_request->set_verification_key_hash(kPolicyVerificationKeyHash);
 
     // These fields are included only in requests for chrome policy.
     if (IsChromePolicy(type_to_fetch.first)) {
       if (submit_machine_id_ && !machine_id_.empty())
         fetch_request->set_machine_id(machine_id_);
-      if (!last_policy_timestamp_.is_null()) {
-        base::TimeDelta timestamp(
-            last_policy_timestamp_ - base::Time::UnixEpoch());
-        fetch_request->set_timestamp(timestamp.InMilliseconds());
-      }
+      if (!last_policy_timestamp_.is_null())
+        fetch_request->set_timestamp(last_policy_timestamp_.ToJavaTime());
       if (!invalidation_payload_.empty()) {
         fetch_request->set_invalidation_version(invalidation_version_);
         fetch_request->set_invalidation_payload(invalidation_payload_);
       }
     }
   }
 
   // Add device state keys.
   if (!state_keys_to_upload_.empty()) {
     em::DeviceStateKeyUpdateRequest* key_update_request =
@@ skipping 526 matching lines @@
   for (auto& observer : observers_)
     observer.OnRobotAuthCodesFetched(this);
 }
 
 void CloudPolicyClient::NotifyClientError() {
   for (auto& observer : observers_)
     observer.OnClientError(this);
 }
 
 }  // namespace policy