The picture is uploaded to rupload.facebook.com/messenger_image/<uuid> through
MessengerMediaUpload, the one owner of a media upload's wire (the header set
the foreign host needs, the entity headers and the owner's error mapping). The
photo posts without a slot, as the only observed messenger_image wire does.
Send a new photo from a gallery.
The picture is uploaded to
rupload.facebook.com/messenger_image/<uuid>throughMessengerMediaUpload, the one owner of a media upload's wire (the header set the foreign host needs, the entity headers and the owner's error mapping). The photo posts without a slot, as the only observedmessenger_imagewire does.