Comment 6 for bug 1500742

Just to be clear - there aren't really any cases where DownloadRequest.mimeType from Oxide should be trusted to make a decision. Even in the case where the download is triggered on the Content-Disposition header where Oxide does know the mime-type, that mime-type becomes untrustworthy the moment we discard the response and ask someone else to do the download instead - at which point the server could respond with something completely different.

Given the problems with this API in Oxide, I would like us to end up in a position where we can deprecate (and eventually remove) DownloadRequest.mimeType without breaking downloads.