Rename isTreatedAsOrStackingContext to isStacked

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

Index: third_party/WebKit/Source/core/paint/PaintLayerStackingNode.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerStackingNode.cpp b/third_party/WebKit/Source/core/paint/PaintLayerStackingNode.cpp
index 03883ee8f4a183607df7634b3cb0d24eef224dc4..d16d3a2e9934b9454de894ff9252a71d32f6c2bf 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerStackingNode.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerStackingNode.cpp
@@ -61,7 +61,7 @@ PaintLayerStackingNode::PaintLayerStackingNode(PaintLayer* layer)
     , m_stackingParent(0)
 #endif
 {
-    m_isTreatedAsOrStackingContext = shouldBeTreatedAsOrStackingContext();
+    m_isStacked = shouldStackObject(*layoutObject());

[chrishtr, 2016/03/16 16:26:16]

Why is this code caching shouldStackObject(*layoutObject())? Can't it be easily
recomputed?

[Xianzhu, 2016/03/16 18:10:24]

According to the comment for
PaintLayerStackingNode::isTreatedAsOrStackingContext() (now isStacked), we need
to save the current value and in future updateIsStacked() we need to do
something when it changes.

[chrishtr, 2016/03/16 18:15:09]

Ok then I suggest renaming updateIsStacked to styleChanged(), and renaming
isStacked() to shouldStackObject (or shouldStackObjectInParentStackingContext,
but that seems long). shouldStackObject should take no arguments.

[Xianzhu, 2016/03/16 21:28:41]

The static shouldStackObject was also for another call from
LayoutBoxModelObject::createLayer() which previously called
ComputedStyle::isTreatedAsOrStackingContext().

The new patch set adds back ComputedStyle::isStacked() so that
LayoutBoxModelObject::createLayer() can call it. I think though isStacked() is a
painting concept, it's convenient to let ComputedStyle provide such a method.

The new patch set also combines
PaintLayerStackingNode::updateStackingNodesAfterStyleChange() and
PaintLayerStackingNode::updateIsStacked() into
PaintLayerStackingNode::styleDidChange().

Should we choose isStacked() instead of shouldStackObject()? I think the
"stacked" is clearly defined in the comments and markdown.

 
     // Non-stacking contexts should have empty z-order lists. As this is already the case,
     // there is no need to dirty / recompute these lists.
@@ -161,7 +161,7 @@ void PaintLayerStackingNode::collectLayers(OwnPtr<Vector<PaintLayerStackingNode*
     if (layer()->isInTopLayer())
         return;
 
-    if (isTreatedAsOrStackingContext()) {
+    if (isStacked()) {
         OwnPtr<Vector<PaintLayerStackingNode*>>& buffer = (zIndex() >= 0) ? posBuffer : negBuffer;
         if (!buffer)
             buffer = adoptPtr(new Vector<PaintLayerStackingNode*>);
@@ -234,13 +234,13 @@ void PaintLayerStackingNode::updateStackingNodesAfterStyleChange(const ComputedS
         clearZOrderLists();
 }
 
-void PaintLayerStackingNode::updateIsTreatedAsStackingContext()
+void PaintLayerStackingNode::updateIsStacked()
 {
-    bool isTreatedAsOrStackingContext = shouldBeTreatedAsOrStackingContext();
-    if (isTreatedAsOrStackingContext == this->isTreatedAsOrStackingContext())
+    bool isStackedContent = shouldStackObject(*layoutObject());
+    if (isStackedContent == m_isStacked)
         return;
 
-    m_isTreatedAsOrStackingContext = isTreatedAsOrStackingContext;
+    m_isStacked = isStackedContent;
     if (!layoutObject()->documentBeingDestroyed() && !layer()->isRootLayer())
         compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
     dirtyStackingContextZOrderLists();