Simplify TransferMode and Color types.

sky/engine/core/painting/CanvasColor.h

Index: sky/engine/core/painting/CanvasColor.h
diff --git a/sky/engine/core/painting/CanvasColor.h b/sky/engine/core/painting/CanvasColor.h
index 43e719c214b0a2ff589acaf0e1c1ee56b8f7bd37..04205f6e4927ed29005a7dfba7ef31da35f90206 100644
--- a/sky/engine/core/painting/CanvasColor.h
+++ b/sky/engine/core/painting/CanvasColor.h
@@ -13,17 +13,14 @@
 
 namespace blink {
 
-class CanvasColor {
- public:
-  SkColor sk_color;
-};
+class CanvasColor {};
 
-template<>
-struct DartConverter<CanvasColor, void> {
-  static CanvasColor FromArgumentsWithNullCheck(Dart_NativeArguments args,
-                                                int index,
-                                                Dart_Handle& exception);
-  static void SetReturnValue(Dart_NativeArguments args, unsigned val);
+template <>
+struct DartConverter<CanvasColor> {
+  static SkColor FromArgumentsWithNullCheck(Dart_NativeArguments args,
+                                            int index,
+                                            Dart_Handle& exception);
+  static void SetReturnValue(Dart_NativeArguments args, SkColor val);
 };
 
 } // namespace blink