Introduce PaintingContext, which will be used for custom painting

sky/engine/core/painting/Paint.h

+// 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_PAINT_H_
+#define SKY_ENGINE_CORE_PAINTING_PAINT_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/SkPaint.h"
+
+namespace blink {
+
+class Paint : public RefCounted<Paint>, public DartWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    ~Paint() override;
+    static PassRefPtr<Paint> create()
+    {
+        return adoptRef(new Paint);
+    }
+
+    bool isAntiAlias() const { return m_paint.isAntiAlias(); }
+    void setIsAntiAlias(bool value) { m_paint.setAntiAlias(value); }
+
+    unsigned color() const { return m_paint.getColor(); }
+    void setColor(unsigned color) { m_paint.setColor(color); }
+
+    void setARGB(unsigned a, unsigned r, unsigned g, unsigned b)
+    {
+        m_paint.setARGB(r, g, b, a);
+    }
+
+    const SkPaint& paint() const { return m_paint; }
+
+private:
+    Paint();
+
+    SkPaint m_paint;
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_PAINTING_PAINT_H_