Get a bitmask indicating which events are handled by the registered callback
#include <OMXAL/OpenMAXAL_QNX.h>
struct XAQNXVideoBufferQueueSourceItf_ {
XAresult (*GetCallbackEventsMask)(XAQNXVideoBufferQueueSourceItf self,
XAuint32 *pEventFlags);
} ;
An XA_RESULT_* constant indicating the operation result