Comment 72 for bug 151162

(From update of attachment 379666)
>+ nsCOMPtr<nsISupports> data;
>+ rv = aTransferable->GetTransferData(kURLMime,
>+

to comply with comment #46 can we make this kFilePromiseURLMime

>+ nsPrimitiveHelpers::CreateDataFromPrimitive(kURLMime,
>+ data,
>+

and here

the url should be in the data for x-moz-file-promise-url

>+ if (strcmp(mimeFlavor, gTextUriListType) == 0 && !mTempFileCreated) {
>+ nsCOMPtr<nsIFile> tmpDir;

a check for kFilePromiseURLMime needed