[SVGDom] Add <circle>, <ellipse> support

experimental/svg/model/SkSVGCircle.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkSVGCircle_DEFINED
+#define SkSVGCircle_DEFINED
+
+#include "SkSVGShape.h"
+#include "SkSVGTypes.h"
+
+class SkSVGCircle final : public SkSVGShape {
+public:
+    virtual ~SkSVGCircle() = default;
+    static sk_sp<SkSVGCircle> Make() { return sk_sp<SkSVGCircle>(new SkSVGCircle()); }
+
+    void setCx(const SkSVGLength&);
+    void setCy(const SkSVGLength&);
+    void setR(const SkSVGLength&);
+
+protected:
+    void onSetAttribute(SkSVGAttribute, const SkSVGValue&) override;
+
+    void onDraw(SkCanvas*, const SkSVGLengthContext&, const SkPaint&) const override;
+
+private:
+    SkSVGCircle();
+
+    SkSVGLength fCx = SkSVGLength(0);
+    SkSVGLength fCy = SkSVGLength(0);
+    SkSVGLength fR  = SkSVGLength(0);
+
+    typedef SkSVGShape INHERITED;
+};
+
+#endif // SkSVGCircle_DEFINED