Re-land "Add a Color class to dart:sky."

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
new file mode 100644
index 0000000000000000000000000000000000000000..43e719c214b0a2ff589acaf0e1c1ee56b8f7bd37
--- /dev/null
+++ b/sky/engine/core/painting/CanvasColor.h
@@ -0,0 +1,31 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef SKY_ENGINE_CORE_PAINTING_CANVASCOLOR_H_
+#define SKY_ENGINE_CORE_PAINTING_CANVASCOLOR_H_
+
+#include "sky/engine/core/painting/Rect.h"
+#include "sky/engine/tonic/dart_wrappable.h"
+#include "sky/engine/wtf/PassRefPtr.h"
+#include "sky/engine/wtf/RefCounted.h"
+#include "third_party/skia/include/core/SkColor.h"
+
+namespace blink {
+
+class CanvasColor {
+ public:
+  SkColor sk_color;
+};
+
+template<>
+struct DartConverter<CanvasColor, void> {
+  static CanvasColor FromArgumentsWithNullCheck(Dart_NativeArguments args,
+                                                int index,
+                                                Dart_Handle& exception);
+  static void SetReturnValue(Dart_NativeArguments args, unsigned val);
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_PAINTING_CANVASCOLOR_H_