Add missing file

osu.Framework/Platform/SDLWindow.cs

@@ -0,0 +1,17 @@
+// 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.
+
+namespace osu.Framework.Platform
+{
+    public class SDLWindow : Window
+    {
+        /// <summary>
+        /// Convenience constructor that uses <see cref="Sdl2WindowBackend"/> and
+        /// <see cref="PassthroughGraphicsBackend"/>.
+        /// </summary>
+        public SDLWindow()
+            : base(new Sdl2WindowBackend(), new PassthroughGraphicsBackend())
+        {
+        }
+    }
+}