Preliminary paint property walk implementation for SPv2

third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h

Index: third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h
diff --git a/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h b/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h
index e656dc8bf1180f32a0d8724275b4823ac6341e67..954d572f0fe1e03c15f9968537040c121abf1dc0 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h
+++ b/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.h
@@ -21,7 +21,7 @@ namespace blink {
 // for the root.
 class PLATFORM_EXPORT TransformPaintPropertyNode : public RefCounted<TransformPaintPropertyNode> {
 public:
-    TransformPaintPropertyNode(const TransformationMatrix& matrix, const FloatPoint3D& origin, PassRefPtr<TransformPaintPropertyNode> parent = nullptr)
+    TransformPaintPropertyNode(const TransformationMatrix& matrix, const FloatPoint3D& origin, TransformPaintPropertyNode* parent = nullptr)

[jbroman, 2015/10/14 15:11:59]

Why this change? PassRefPtr<T> is implicitly constructible from T* (so this
doesn't make callers work that otherwise wouldn't), but this change precludes
passing existing ownership if desired, and makes it less clear that this
constructor owns a reference.

[trchen, 2015/10/14 22:51:13]

You're right. I don't know what I was thinking. Reverted.

         : m_matrix(matrix), m_origin(origin), m_parent(parent) { }
 
     const TransformationMatrix& matrix() const { return m_matrix; }