1b51797326
One annoying part to this is that for "Save As" downloads on a PDF (for example), we don't get a valid browsing context. For downloads, the only thing we need a browsing context for us to get a window so we can show the "DLP busy" notification, so just use the window that we were initialized with. In practice I can't tell any difference. Original Revision: https://phabricator.services.mozilla.com/D251880 Differential Revision: https://phabricator.services.mozilla.com/D258204