When user chooses to save to PDF we open the document chooser UI.
Now if the user now backs to the print UI without choosing a file,
the print UI has all options disabled and the back button does
not work - the user is stuck. This is because we were not
transitioning the print UI in the correct state.
bug:17557454
Change-Id: I385129e106ed41564b89137ca54d409127ba8ff0