Make KeyBindingOverlay support variants as settings sub sections.

osu.Game/Overlays/KeyBinding/KeyBindingsSubsection.cs

@@ -0,0 +1,44 @@
+// 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.Collections.Generic;
+using System.Linq;
+using osu.Framework.Allocation;
+using osu.Game.Input;
+using osu.Game.Overlays.Settings;
+using osu.Game.Rulesets;
+using OpenTK;
+
+namespace osu.Game.Overlays.KeyBinding
+{
+    public abstract class KeyBindingsSubsection : SettingsSubsection
+    {
+        protected IEnumerable<Framework.Input.Bindings.KeyBinding> Defaults;
+
+        protected RulesetInfo Ruleset;
+
+        private readonly int variant;
+
+        protected KeyBindingsSubsection(int variant)
+        {
+            this.variant = variant;
+
+            FlowContent.Spacing = new Vector2(0, 1);
+        }
+
+        [BackgroundDependencyLoader]
+        private void load(KeyBindingStore store)
+        {
+            var bindings = store.Query(Ruleset?.ID, variant);
+
+            foreach (var defaultBinding in Defaults)
+            {
+                // one row per valid action.
+                Add(new KeyBindingRow(defaultBinding.Action, bindings.Where(b => b.Action.Equals((int)defaultBinding.Action)))
+                {
+                    AllowMainMouseButtons = Ruleset != null
+                });
+            }
+        }
+    }
+}