Repro:
1. Setup a device with kiosk apps
   (whether to auto launch does not matter);
2. "stop ui" as root to stop chrome 
3. "rm /home/chronos/Local\ State" to delete the "Local State" file
4. "start ui" to run chrome again. This time the device should
   land on OOBE page since it losts the state;
5. "restart ui"

At step 5, one would expect to see OOBE screen again. But that does not happen, the device shows a black screen and would stay in state no matter how many time it boots.

The reason is that the login screen is waiting for wallpaper to load. With the combination of kiosk as users and restored "Local State", the wallpaper load never happens. Hence login screen stuck there forever.