A proof of concept for annular sector layout.

sky/engine/core/painting/CanvasPath.h

Index: sky/engine/core/painting/CanvasPath.h
diff --git a/sky/engine/core/painting/CanvasPath.h b/sky/engine/core/painting/CanvasPath.h
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+// 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_PATH_H_
+#define SKY_ENGINE_CORE_PAINTING_PATH_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/SkPath.h"
+
+// Note: There's a very similar class in ../../platform/graphics/Path.h
+// We should probably rationalise these two.
+// (The existence of that class is why this is CanvasPath and not just Path.)
+
+namespace blink {
+
+class CanvasPath : public RefCounted<CanvasPath>, public DartWrappable {
+    DEFINE_WRAPPERTYPEINFO();
+public:
+    ~CanvasPath() override;
+    static PassRefPtr<CanvasPath> create()
+    {
+        return adoptRef(new CanvasPath);
+    }
+
+    void moveTo(float x, float y)
+    {
+        m_path.moveTo(x, y);
+    }
+
+    void lineTo(float x, float y)
+    {
+        m_path.lineTo(x, y);
+    }
+
+    void arcTo(const Rect& rect, float startAngle, float sweepAngle, bool forceMoveTo)
+    {
+        m_path.arcTo(rect.sk_rect, startAngle, sweepAngle, forceMoveTo);
+    }
+
+    void close()
+    {
+        m_path.close();
+    }
+
+    const SkPath& path() const { return m_path; }
+
+private:
+    CanvasPath();
+
+    SkPath m_path;
+};
+
+} // namespace blink
+
+#endif  // SKY_ENGINE_CORE_PAINTING_PATH_H_