[GnomeSession] split out the gnome-session presence D-Bus interface

Split this out of js/ui/statusMenu.js

https://bugzilla.gnome.org/show_bug.cgi?id=608667

js/misc/gnomeSession.js

@@ -0,0 +1,45 @@
+/* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */
+
+const DBus = imports.dbus;
+const Lang = imports.lang;
+
+const PresenceIface = {
+    name: 'org.gnome.SessionManager.Presence',
+    methods: [{ name: 'SetStatus',
+                inSignature: 'u' }],
+    properties: [{ name: 'status',
+                   signature: 'u',
+                   access: 'readwrite' }],
+    signals: [{ name: 'StatusChanged',
+                inSignature: 'u' }]
+};
+
+const PresenceStatus = {
+    AVAILABLE: 0,
+    INVISIBLE: 1,
+    BUSY: 2,
+    IDLE: 3
+};
+
+function Presence() {
+    this._init();
+}
+
+Presence.prototype = {
+    _init: function() {
+        DBus.session.proxifyObject(this, 'org.gnome.SessionManager', '/org/gnome/SessionManager/Presence', this);
+    },
+
+    getStatus: function(callback) {
+        this.GetRemote('status', Lang.bind(this,
+            function(status, ex) {
+                if (!ex)
+                    callback(this, status);
+            }));
+    },
+
+    setStatus: function(status) {
+        this.SetStatusRemote(status);
+    }
+};
+DBus.proxifyPrototype(Presence.prototype, PresenceIface);