[Sync] use base::Time in sync

chrome/browser/sync/util/time.cc

+// Copyright (c) 2011 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/sync/util/time.h"
+
+#include "base/i18n/time_formatting.h"
+#include "base/utf_string_conversions.h"
+
+namespace browser_sync {
+
+int64 TimeToProtoTime(const base::Time& t) {
+  return (t - base::Time::UnixEpoch()).InMilliseconds();
+}
+
+base::Time ProtoTimeToTime(int64 proto_t) {
+  return base::Time::UnixEpoch() + base::TimeDelta::FromMilliseconds(proto_t);
+}
+
+std::string GetTimeDebugString(const base::Time& t) {
+  return UTF16ToUTF8(base::TimeFormatFriendlyDateAndTime(t));
+}
+
+}  // namespace browser_sync