Check DreamActivity callback type to prevent class cast exception

This keeps the type-checking introduced in http://ag/21518427, but removes the NO_HISTORY flag which causes the lowlight system dream on tablets to break

This reverts commit be56335883fc2b1e207ec3db5b473a83c566172b.

Reason for revert: fix-forward

Change-Id: Idc5ce791fb07f2a7a181fb0b875bf001968b6889
1 file changed