added confirmation dialog for Delete ALL beatmaps

osu.Game/Overlays/Settings/Sections/Maintenance/DeleteAllBeatmapsDialog.cs

@@ -0,0 +1,46 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using osu.Framework.Allocation;
+using osu.Game.Beatmaps;
+using osu.Game.Graphics;
+using osu.Game.Overlays.Dialog;
+
+namespace osu.Game.Overlays.Settings.Sections.Maintenance
+{
+    public class DeleteAllBeatmapsDialog : PopupDialog
+    {
+        private BeatmapManager manager;
+
+        [BackgroundDependencyLoader]
+        private void load(BeatmapManager beatmapManager)
+        {
+            manager = beatmapManager;
+        }
+
+        public DeleteAllBeatmapsDialog(Action deleteAction)
+        {
+            BodyText = "Everything?";
+
+            Icon = FontAwesome.fa_trash_o;
+            HeaderText = @"Confirm deletion of";
+            Buttons = new PopupDialogButton[]
+            {
+                new PopupDialogOkButton
+                {
+                    Text = @"Yes. Go for it.",
+                    Action = deleteAction
+                },
+                new PopupDialogCancelButton
+                {
+                    Text = @"No! Abort mission!",
+                },
+            };
+        }
+    }
+}