Add skin config lookup for combo colours

osu.Game/Skinning/SkinComboColourLookup.cs

@@ -0,0 +1,26 @@
+// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
+// See the LICENCE file in the repository root for full licence text.
+
+using osu.Game.Rulesets.Objects.Types;
+
+namespace osu.Game.Skinning
+{
+    public class SkinComboColourLookup
+    {
+        /// <summary>
+        /// The index to use for deciding the combo colour.
+        /// </summary>
+        public readonly int ColourIndex;
+
+        /// <summary>
+        /// The combo information requesting the colour.
+        /// </summary>
+        public readonly IHasComboInformation Combo;
+
+        public SkinComboColourLookup(int colourIndex, IHasComboInformation combo)
+        {
+            ColourIndex = colourIndex;
+            Combo = combo;
+        }
+    }
+}

osu.Game/Skinning/SkinProvidingContainer.cs

@@ -72,7 +72,7 @@ namespace osu.Game.Skinning
         {
             if (skin != null)
             {
-                if (lookup is GlobalSkinColours || lookup is SkinCustomColourLookup)
+                if (lookup is GlobalSkinColours || lookup is SkinComboColourLookup || lookup is SkinCustomColourLookup)
                     return lookupWithFallback<TLookup, TValue>(lookup, AllowColourLookup);
 
                 return lookupWithFallback<TLookup, TValue>(lookup, AllowConfigurationLookup);