We keep per user settings for enabled print services which are
observed to update the print manager service state. We were listening
to all user changes but the handling code was not updating the state
of the user whose settings changed, rather the current user.
Added hidden APIs in content observer to know which user changed
and now the print manager serivce handles content changes for the
correct user.
bug:16977006
Change-Id: I71ec88c8f3f38cb405844c13ab83695c2029eb79
86b1df2343