The purpose of this CL is to use jlongFromPointer() for converting frame pointers to jlong instead of implicit casts which is not safe. In order to respect constness, I had to make a small helper function for this. BUG=webrtc:4993 R=perkj@webrtc.org Review URL: https://codereview.webrtc.org/1373233002 . Cr-Commit-Position: refs/heads/master@{#10108}