The browser calls this function once after the last instance of your plug-in is destroyed, before unloading the plug-in library itself. Use NP_Shutdown to delete any data allocated in NP_Initialize to be shared by all instances of a plug-in.
NOTE: If enough memory is available, the browser can keep the plug-in library loaded if it expects to create more instances in the near future. The browser calls NP_Shutdown only when the library is finally unloaded. §