Check that the parcel contained the expected amount of region data. DO NOT MERGE

bug:20883006
Change-Id: Ib47a8ec8696dbc37e958b8dbceb43fcbabf6605b

 RgnIterPair(const SkRegion& rgn) : fRgn(rgn) {
        fIter.reset(fRgn);
 }

 RgnIterPair(const SkRegion& rgn) : fRgn(rgn) {
        fIter.reset(fRgn);
 }
