Comment 6 for bug 1303962

As a follow-on, here is the introspection data for the thumbnailer D-Bus service:

http://bazaar.launchpad.net/~unity-team/thumbnailer/trunk/view/head:/src/service/dbus-interface.xml

The file data is returned by passing a read-only file descriptor for a file in ~/.cache/media-art, and the content of that file is only dependent on the artist and album name in the method call.