Move computation of 3D descendants to the descendant-dependent flags walk.

third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp

Index: third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
index 6baebf02bfb5a7794626ffa4a5af5af5d5137593..1521b9de637b5ac19d944f3acd194213801ca099 100644
--- a/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintPropertyTreeBuilder.cpp
@@ -307,25 +307,23 @@ void PaintPropertyTreeBuilder::updateTransformForNonRootSVG(
 
 static CompositingReasons compositingReasonsForTransform(
     const LayoutObject& object) {
+  const ComputedStyle& style = object.styleRef();
   CompositingReasons compositingReasons = CompositingReasonNone;
   if (CompositingReasonFinder::requiresCompositingForTransform(object))
     compositingReasons |= CompositingReason3DTransform;
 
-  if (CompositingReasonFinder::requiresCompositingForTransformAnimation(
-          object.styleRef()))
+  if (CompositingReasonFinder::requiresCompositingForTransformAnimation(style))
     compositingReasons |= CompositingReasonActiveAnimation;
 
-  if (object.styleRef().hasWillChangeCompositingHint() &&
-      !object.styleRef().subtreeWillChangeContents())
+  if (style.hasWillChangeCompositingHint() &&
+      !style.subtreeWillChangeContents())
     compositingReasons |= CompositingReasonWillChangeCompositingHint;
 
-  if (object.isBoxModelObject()) {
+  if (object.isBoxModelObject() &&

[Xianzhu, 2016/12/28 18:08:11]

Not related to the change, but just a question: we support non-box object here,
but don't  in updateTransform() (which doesn't create transform node if
!object.isBox()). Is there any problem?

+      (style.hasPerspective() ||
+       style.usedTransformStyle3D() == TransformStyle3DPreserve3D)) {
     const LayoutBoxModelObject* box = toLayoutBoxModelObject(&object);
     if (box->hasLayer()) {
-      // TODO(chrishtr): move this to the descendant-dependent flags recursion
-      // PaintLayer::updateDescendantDependentFlags.
-      box->layer()->update3DTransformedDescendantStatus();
-
       if (box->layer()->has3DTransformedDescendant())
         compositingReasons |= CompositingReason3DTransform;
     }