ScreenShield: send a signal to GSD to wake up the screen

Instead of poking through IDLETIME, which confuses the state tracking
and can prevent automatic suspend, send a special signal to GSD
when the screen is to be waken up for a notification.

Someday we'll bring over all the state tracking and avoid this
ping-pong between gnome-shell and gnome-settings-daemon, but
that day's not today.

https://bugzilla.gnome.org/show_bug.cgi?id=712706

js/ui/shellDBus.js

@@ -69,6 +69,7 @@ const ScreenSaverIface = '<node> \
 <signal name="ActiveChanged"> \
     <arg name="new_value" type="b" /> \
 </signal> \
+<signal name="WakeUpScreen" /> \
 </interface> \
 </node>';
 
@@ -407,6 +408,9 @@ const ScreenSaverDBus = new Lang.Class({
         screenShield.connect('active-changed', Lang.bind(this, function(shield) {
             this._dbusImpl.emit_signal('ActiveChanged', GLib.Variant.new('(b)', [shield.active]));
         }));
+        screenShield.connect('wake-up-screen', Lang.bind(this, function(shield) {
+            this._dbusImpl.emit_signal('WakeUpScreen', null);
+        }));
 
         this._dbusImpl = Gio.DBusExportedObject.wrapJSObject(ScreenSaverIface, this);
         this._dbusImpl.export(Gio.DBus.session, '/org/gnome/ScreenSaver');