Sky: Added radial gradients.

sky/engine/core/painting/CanvasGradient.h

Index: sky/engine/core/painting/CanvasGradient.h
diff --git a/sky/engine/core/painting/CanvasGradient.h b/sky/engine/core/painting/CanvasGradient.h
index 7d8ea19843df30095e17edb91504301822e69689..fed61ec3d7cd2efa943c099bac65bcdb21678777 100644
--- a/sky/engine/core/painting/CanvasGradient.h
+++ b/sky/engine/core/painting/CanvasGradient.h
@@ -17,13 +17,18 @@ class CanvasGradient : public Shader {
     DEFINE_WRAPPERTYPEINFO();
  public:
   ~CanvasGradient() override;
-  static PassRefPtr<CanvasGradient> create(int type,
-                                           const Vector<Point>& end_points,
-                                           const Vector<SkColor>& colors,
-                                           const Vector<float>& color_stops);
+  static PassRefPtr<CanvasGradient> create();
+
+  void initLinear(const Vector<Point>& end_points,
+                  const Vector<SkColor>& colors,
+                  const Vector<float>& color_stops);
+  void initRadial(const Point& center,
+                  double radius,
+                  const Vector<SkColor>& colors,
+                  const Vector<float>& color_stops);
 
  private:
-  CanvasGradient(PassRefPtr<SkShader> shader);
+  CanvasGradient();
 };
 
 } // namespace blink