Crash in print spooler if printing app killed from recents.

If the printing app with the print UI on top is killed from recents we get
a crash because: 1) the remote print document was not transitioned to a
failed state if the printing app dies (this is an unrecoverable failure);
2) the print preview controller was destroyed asyncronosly during which it
also asynchronously disconnects from the rendering service which however
happens after the system has already cleaned up all connections of the print
UI activity as it is being destoryed.

bug:18109386

Change-Id: If6200b14a8aa90622228bbb659e9c4962226f561