Issue 844923  has been merged into this issue.

So this uses progress events, but the way it does that suggests that DownloadAsStream is actually a very good fit for what it's doing.

Please check whether https://chromium-review.googlesource.com/c/chromium/src/+/1050825 covers this.

It does; thank you for catching this (how did you manage that?)

Probably a good thing, too, since the upload bit would have been way tougher for me than for Matt.