* @mem_share: the implementation of the GstMemoryShareFunction
* @mem_is_span: the implementation of the GstMemoryIsSpanFunction
* @mem_map_full: the implementation of the GstMemoryMapFullFunction.
* @mem_share: the implementation of the GstMemoryShareFunction
* @mem_is_span: the implementation of the GstMemoryIsSpanFunction
* @mem_map_full: the implementation of the GstMemoryMapFullFunction.