[Download Job] Show referrer instead of data URL
A data URL isn't very meaningful to the user, so show the referrer URL as download source. Also store it in origin URL attribute since a data URL contains no origin and also isn't very useful as it just contains the data of the file we've just downloaded.
- in Chrome downloaded a file from Google image search. While prompting for a filename, I got a "Downloading: 1 file" instead of a gibberish file name because Source as www.google.com now with no file name
- once a filename was chosen, it was displayed during the download as before
- the downloaded file now contained "www.google.com" as "downloaded from" address which is at least somewhat descriptive of the file's whereabouts
- Firefox only gave me a
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referrer in this scenario, though