Closed requested to merge jbicha/totem:mute-action into master
This allows "Mute" to be exported as a D-Bus action.
Ubuntu uses this action as one of its Desktop Actions
The Desktop Actions were rejected from inclusion in GNOME years ago because they are static instead of dynamic run-time actions (so the actions like Play and Mute show even when the app is closed and no video is playing). See https://bugzilla.gnome.org/671088