Move scroll paint property nodes to be owned by the transform tree

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

Index: third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.cpp
diff --git a/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.cpp b/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.cpp
index 7796b1a9d2432afde6d1ed8e6cae2a7ae308cb27..4e86f406f69aa50385975341f38500c4a2d8befe 100644
--- a/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.cpp
+++ b/third_party/WebKit/Source/platform/graphics/paint/TransformPaintPropertyNode.cpp
@@ -8,17 +8,19 @@
 
 namespace blink {
 
+// The root of the transform tree. The root transform node references the root
+// scroll node.
 TransformPaintPropertyNode* TransformPaintPropertyNode::root() {
   DEFINE_STATIC_REF(TransformPaintPropertyNode, root,
-                    (TransformPaintPropertyNode::create(
-                        nullptr, TransformationMatrix(), FloatPoint3D(),
+                    adoptRef(new TransformPaintPropertyNode(
+                        nullptr, TransformationMatrix(), FloatPoint3D(), false,
+                        0, CompositingReasonNone, CompositorElementId(),
                         ScrollPaintPropertyNode::root())));
   return root;
 }
 
-// TODO(pdr): print out scroll node information.
 String TransformPaintPropertyNode::toString() const {
-  return String::format(
+  auto transform = String::format(
       "parent=%p transform=%s origin=%s flattensInheritedTransform=%s "
       "renderingContextId=%x directCompositingReasons=%s "
       "compositorElementId=(%d, %d)",
@@ -27,6 +29,9 @@ String TransformPaintPropertyNode::toString() const {
       m_flattensInheritedTransform ? "yes" : "no", m_renderingContextId,
       compositingReasonsAsString(m_directCompositingReasons).ascii().data(),
       m_compositorElementId.primaryId, m_compositorElementId.secondaryId);
+  if (m_scroll)
+    return transform + " scroll=" + m_scroll->toString();
+  return transform;
 }
 
 #if DCHECK_IS_ON()