Add tlsdate user to LibCrosService DBus ACL

chrome/browser/chromeos/dbus/org.chromium.LibCrosService.conf

 <!DOCTYPE busconfig PUBLIC "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
   "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
 <!--
   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.
 
   This file will be installed at /etc/dbus-1/system.d on Chromium OS.
 -->
 <busconfig>
   <policy user="chronos">
     <allow own="org.chromium.LibCrosService"/>
     <allow receive_sender="org.chromium.LibCrosService"/>
     <allow send_destination="org.chromium.LibCrosService"/>
   </policy>
 
   <!-- bluez makes agent method calls to Chromium. -->
   <policy user="bluetooth">
     <allow send_destination="org.chromium.LibCrosService"/>
   </policy>
 
   <!-- tlsdate needs to query proxy config. -->
+  <policy user="tlsdate">
+    <allow send_destination="org.chromium.LibCrosService"/>
+  </policy>
+  <!-- TODO(cmasone): proxystate user is deprecated. crbug.com/376526 -->
   <policy user="proxystate">
     <allow send_destination="org.chromium.LibCrosService"/>
   </policy>
 
   <!-- powerd needs to change display power states. -->
   <policy user="power">
     <allow send_destination="org.chromium.LibCrosService"/>
   </policy>
 
   <!-- update_engine uses this service to resolve the proxy config. -->
   <policy user="root">
     <allow send_destination="org.chromium.LibCrosService"/>
   </policy>
 </busconfig>