Prepare "grant permissions" for Tv-specific view handler.

Also, this cleans up some unused code in GrantPermissionsActivity
and fixes a latent bug in GrantPermissionsActivity#updateDefaultResults
where if the calling package was null, we were defaulting to GRANTED.

Note that we can't simply create a tv-specific layout xml file,
because the view handler is tied to the layout xml, so this change
allows for the creation of different view handlers.

b/20476102

Change-Id: Ia62051a0895e4bd314d18ba3001871b29de21ae5