This will replace the indicator painted on the stage right now.
This unfortunately does not work for the recorder triggered by the
keybinding -- we'll simply replace the in-shell code with a keybinding
powered by gnome-settings-daemon.
If we are passed an invalid file template, ShellRecorder.record()
will return a %NULL filename; as the Screencast DBus interface
expects a string return value, we cannot return the value unmodified
in that case.
https://bugzilla.gnome.org/show_bug.cgi?id=700842
Like screenshots, the screen recorder can be a useful tool in other cases
than being triggered by a keyboard shortcut. To account for that, export
a Screencast DBus API similar to the existing Screenshot interface.
https://bugzilla.gnome.org/show_bug.cgi?id=696247
