Helper Apps (and a bit of Save As) - Archive of obsolete content
the nsexternalhelperappservice looks up the nsimimeinfo for the load and creates an nsihelperapplauncher to manage the load.
... the nsexternalapphandler (which implements nsihelperapplauncher) uses the nsimimeinfo and an nsihelperapplauncherdialog to decide what to do with the data.
... nsimimeinfo lookup look in built-in list which the user cannot override (types we handle internally).
...And 3 more matches

nsIDownloadManager
to get the service, use: var downloadmanager = components.classes["@mozilla.org/download-manager;1"] .getservice(components.interfaces.nsidownloadmanager); method overview nsidownload adddownload(in short adownloadtype, in nsiuri asource, in nsiuri atarget, in astring adisplayname, in nsimimeinfo amimeinfo, in prtime astarttime, in nsilocalfile atempfile, in nsicancelable acancelable, in boolean aisprivate); void addlistener(in nsidownloadprogresslistener alistener); void canceldownload(in unsigned long aid); void cleanup(); void endbatchupdate(); obsolete since gecko 1.9.1 void flush(); obsolete since gecko 1.8 nsidownload getdownloa...
... nsidownload adddownload( in short adownloadtype, in nsiuri asource, in nsiuri atarget, in astring adisplayname, in nsimimeinfo amimeinfo, in prtime astarttime, in nsilocalfile atempfile, in nsicancelable acancelable, in boolean aisprivate ); parameters adownloadtype the download type for the transfer.

The Download Manager schema - Archive of obsolete content
preferredaction integer the action constant from nsimimeinfo representing the action to take upon completing the download.

nsIDownload
mimeinfo nsimimeinfo provides the targets relevant mime information, including its mime type, helper application, and whether or not the helper should be executed automatically once the download is complete.

nsIExternalHelperAppService
aforcesave true to always save this content to disk, regardless of nsimimeinfo and other such influences.