Implement notifications.

osu.Game/Overlays/Toolbar/ToolbarNotificationButton.cs

@@ -0,0 +1,28 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using osu.Framework.Allocation;
+using osu.Framework.Graphics;
+using osu.Game.Graphics;
+
+namespace osu.Game.Overlays.Toolbar
+{
+    class ToolbarNotificationButton : ToolbarOverlayToggleButton
+    {
+        protected override Anchor TooltipAnchor => Anchor.TopRight;
+
+        public ToolbarNotificationButton()
+        {
+            Icon = FontAwesome.fa_bars;
+            TooltipMain = "Notifications";
+            TooltipSub = "Waiting for 'ya";
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(NotificationManager notificationManager)
+        {
+            StateContainer = notificationManager;
+            Action = notificationManager.ToggleVisibility;
+        }
+    }
+}