Add support to auto-shutdown on lid close if no one is logged in

src/platform/init/ui.conf

 # Copyright (c) 2009 The Chromium OS Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 description   "Chrome OS user interface"
 author        "chromium-os-dev@googlegroups.com"
 
 start on stopping startup
 stop on starting halt or starting reboot
 
 respawn
 
 pre-start script
 
 X_SOCKET_DIR=/tmp/.X11-unix
 X_ICE_DIR=/tmp/.ICE-unix
 mkdir -p "$X_SOCKET_DIR" "$X_ICE_DIR"
 chown root:root "$X_SOCKET_DIR" "$X_ICE_DIR"
 chmod 1777 "$X_SOCKET_DIR" "$X_ICE_DIR"
 
+# make sure we we can easily track ui state
+rm -rf /var/run/state/
+mkdir -p /var/run/state
+
 end script
 
 #expect fork
 #exec /usr/bin/slim -d
 # To switch back to deprecated slim-based login functionality, comment out the
 # following and uncomment the two lines above.
 exec /sbin/session_manager_setup.sh
 
 post-stop script
 
 set +e
 . /sbin/killers
 kill_with_open_files_on /home/chronos/user
 term_process "^X$"
 # Eventually, this will take a parameter specifying which user's dir to unmount.
 exec /usr/sbin/umount.cryptohome
 
 end script