Reuse existing paint property node is possible

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

Index: third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.h
diff --git a/third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.h b/third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.h
index 943de30cdc924214168aed3e957b07db631e2ea8..40ed0288c79385d38478fc9005edd95ec2b204ef 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.h
+++ b/third_party/WebKit/Source/platform/graphics/paint/ClipPaintPropertyNode.h
@@ -21,6 +21,8 @@ namespace blink {
 // and an (optional) parent ClipPaintPropertyNode for inherited clips.
 class PLATFORM_EXPORT ClipPaintPropertyNode : public RefCounted<ClipPaintPropertyNode> {
 public:
+    using Value = FloatRoundedRect;

[pdr., 2016/07/21 21:34:07]

Can a refptr to the local transform space be included in the value so we don't
need to special-case local transform space?

+
     static PassRefPtr<ClipPaintPropertyNode> create(
         PassRefPtr<TransformPaintPropertyNode> localTransformSpace,
         const FloatRoundedRect& clipRect,
@@ -29,12 +31,28 @@ public:
         return adoptRef(new ClipPaintPropertyNode(localTransformSpace, clipRect, parent));
     }
 
+    // This form is required by PaintPropertyTreeBuilder::updateObjectPaintProperties().
+    static PassRefPtr<ClipPaintPropertyNode> create(const Value& value, PassRefPtr<ClipPaintPropertyNode> parent)
+    {
+        return adoptRef(new ClipPaintPropertyNode(nullptr, value, parent));
+    }
+
     const TransformPaintPropertyNode* localTransformSpace() const { return m_localTransformSpace.get(); }
+    const Value& value() const { return m_clipRect; }
     const FloatRoundedRect& clipRect() const { return m_clipRect; }
 
     // Reference to inherited clips, or nullptr if this is the only clip.
     const ClipPaintPropertyNode* parent() const { return m_parent.get(); }
 
+    // Moves this node and its subtrees under another parent.
+    void setParent(PassRefPtr<ClipPaintPropertyNode> parent) { m_parent = parent; }
+
+    // This is separate from the create() method for child node for two purposes:
+    // 1. to let the method have the same parameter list as the method of other paint
+    //    property node classes, so that they can be used in the same template;

[pdr., 2016/07/21 21:34:06]

Nit: ; -> .

+    // 2. to allow to reuse an existing node in a new tree.
+    void setLocalTransformSpace(PassRefPtr<TransformPaintPropertyNode> localTransformSpace) { m_localTransformSpace = localTransformSpace; }
+
 private:
     ClipPaintPropertyNode(PassRefPtr<TransformPaintPropertyNode> localTransformSpace, const FloatRoundedRect& clipRect, PassRefPtr<ClipPaintPropertyNode> parent)
         : m_localTransformSpace(localTransformSpace), m_clipRect(clipRect), m_parent(parent) { }