Backport ChooserTarget package source check from N

Fix a bug where a ChooserTargetService could supply a ChooserTarget
pointing at a non-exported activity outside of its own package and
have it launch.

Bug 28384423

Change-Id: I3f5854f91c5695ad9253d71055ef58224df47008
(cherry picked from commit 82b9565bd13e2c5dac20b3221b7be28c5afe57ea)
1 file changed