nsCOMPtr<nsIDirectoryServiceProvider> prov = do_QueryInterface(aElement); if (!prov) return PR_FALSE;
static PRBool FindProviderFile(nsISupports* aElement, void *aData){  nsresult rv;  nsCOMPtr<nsIDirectoryServiceProvider> prov = do_QueryInterface(aElement);  if (!prov)      return PR_FALSE;  FileData* fileData = (FileData*)aData;  rv = prov->GetFile(fileData->property, &fileData->persistent, &(fileData->file) );  if (NS_SUCCEEDED(rv) && fileData->file)      return PR_FALSE;  return PR_TRUE;}