Wrap stroke mix shell

src/legacy_canvas_stroke_execution_services.h

@@ -562,6 +562,19 @@ execute_legacy_canvas_stroke_mix_pass_with_setup(
     return result;
 }
 
+template <typename BeginMixPass, typename EndMixPass>
+[[nodiscard]] inline LegacyCanvasStrokeMixPassResult
+execute_legacy_canvas_stroke_mix_pass_shell(
+    BeginMixPass&& begin_mix_pass,
+    EndMixPass&& end_mix_pass,
+    const LegacyCanvasStrokeMixPassRequest& request)
+{
+    return execute_legacy_canvas_stroke_mix_pass_with_setup(
+        std::forward<BeginMixPass>(begin_mix_pass),
+        std::forward<EndMixPass>(end_mix_pass),
+        request);
+}
+
 struct LegacyCanvasStrokeComputeRequest {
     StrokeSample previous_sample {};
     std::span<const StrokeSample> samples;