Also allow apps to read the contents of mounted OBBs. See AOSP Change-Id: I66df236eade3ca25a10749dd43d173ff4628cfad and Change-Id: I49b722b24c1c7d9ab084ebee7c1e349d8d660ffa Change-Id: I757a2a8831c69d41c0496025a39eaf79ceb0e65f