Any Android specific modifications to upstream libpng (the version specified in METADATA) should be listed here: (1) Android has added the following files. pngusr.h Android.bp CleanSpec.mk MODULE_LICENSE_BSD_LIKE METADATA OWNERS (2) pnglibconf.h This is copied from scripts/pnglibconf.h.prebuilt. Android has undefined PNG_WARNINGS_SUPPORTED and PNG_READ_OPT_PLTE_SUPPORTED.