Bind volume scale with player volume prop

Now that player API itself is operating on a cubic scale (no value conversion required), the volume slider can be bind to the volume property. Thanks to that, player volume scale will correctly reflect Clapper volume set via external applications e.g. gnome-settings.

src/widget.js

@@ -65,16 +65,16 @@ class ClapperWidget extends Gtk.Grid
         const playerWidget = this.player.widget;
 
         this.controls.elapsedButton.scrolledWindow.set_child(this.player.playlistWidget);
+
         this.controls.speedAdjustment.bind_property(
             'value', this.player, 'rate', GObject.BindingFlags.BIDIRECTIONAL
         );
-
+        this.controls.volumeAdjustment.bind_property(
+            'value', this.player, 'volume', GObject.BindingFlags.BIDIRECTIONAL
+        );
         this.player.connect('position-updated', this._onPlayerPositionUpdated.bind(this));
         this.player.connect('duration-changed', this._onPlayerDurationChanged.bind(this));
 
-        /* FIXME: re-enable once ported to new GstPlayer API with messages bus */
-        //this.player.connect('volume-changed', this._onPlayerVolumeChanged.bind(this));
-
         this.overlay.set_child(playerWidget);
         this.overlay.add_overlay(this.revealerTop);
         this.overlay.add_overlay(this.revealerBottom);
@@ -528,21 +528,6 @@ class ClapperWidget extends Gtk.Grid
         this.controls.positionScale.set_value(positionSeconds);
     }
 
-    _onPlayerVolumeChanged(player)
-    {
-        const volume = player.volume;
-
-        /* FIXME: This check should not be needed, GstPlayer should not
-         * emit 'volume-changed' with the same values, but it does. */
-        if(volume === this.controls.currentVolume)
-            return;
-
-        /* Once above is fixed in GstPlayer, remove this var too */
-        this.controls.currentVolume = volume;
-
-        this.controls._updateVolumeButtonIcon(volume);
-    }
-
     _onStateNotify(toplevel)
     {
         const isMaximized = Boolean(