Chain a bufferlist to pad.
The function returns GST_FLOW_FLUSHING if the pad was flushing.
If pad was not negotiated properly with a CAPS event, this function returns GST_FLOW_NOT_NEGOTIATED
The function proceeds calling the chainlist function installed on pad (see Pad.setChainListFunction) and the return value of that function is returned to the caller. GST_FLOW_NOT_SUPPORTED is returned if pad has no chainlist function.
In all cases, success or failure, the caller loses its reference to list after calling this function.