Revert "Switch DPLStackingNode to use LayoutBoxModelObject"

This reverts commit 3c21051c2de67b51e59ca99c99a4f3ed7d66a3d2.

This is also a cleaner merge of trunk's revert:
https://codereview.chromium.org/1346103003.

BUG=527927

Review URL: https://codereview.chromium.org/1385743004 .

Cr-Commit-Position: refs/branch-heads/2490@{#494}
Cr-Branched-From: 7790a3535f2a81a03685eca31a32cf69ae0c114f-refs/heads/master@{#344925}

4 files changed, 61 insertions, 62 deletions

diff --git a/third_party/WebKit/Source/core/paint/DeprecatedPaintLayer.cpp b/third_party/WebKit/Source/core/paint/DeprecatedPaintLayer.cpp
index a767aca..7504710 100644
--- a/third_party/WebKit/Source/core/paint/DeprecatedPaintLayer.cpp
+++ b/third_party/WebKit/Source/core/paint/DeprecatedPaintLayer.cpp
@@ -1350,7 +1350,7 @@ void DeprecatedPaintLayer::updateStackingNode()
 {
     ASSERT(!m_stackingNode);
     if (requiresStackingNode())
-        m_stackingNode = adoptPtr(new DeprecatedPaintLayerStackingNode(*layoutObject()));
+        m_stackingNode = adoptPtr(new DeprecatedPaintLayerStackingNode(this));
 }
 
 void DeprecatedPaintLayer::updateScrollableArea()
@@ -1524,6 +1524,12 @@ Node* DeprecatedPaintLayer::enclosingElement() const
     return 0;
 }
 
+bool DeprecatedPaintLayer::isInTopLayer() const
+{
+    Node* node = layoutObject()->node();
+    return node && node->isElementNode() && toElement(node)->isInTopLayer();
+}
+
 // Compute the z-offset of the point in the transformState.
 // This is effectively projecting a ray normal to the plane of ancestor, finding where that
 // ray intersects target, and computing the z delta between those two points.
diff --git a/third_party/WebKit/Source/core/paint/DeprecatedPaintLayer.h b/third_party/WebKit/Source/core/paint/DeprecatedPaintLayer.h
index b474e98..8fe5ea5 100644
--- a/third_party/WebKit/Source/core/paint/DeprecatedPaintLayer.h
+++ b/third_party/WebKit/Source/core/paint/DeprecatedPaintLayer.h
@@ -375,6 +375,8 @@ public:
 
     Node* enclosingElement() const;
 
+    bool isInTopLayer() const;
+
     bool scrollsWithViewport() const;
     bool scrollsWithRespectTo(const DeprecatedPaintLayer*) const;
 
diff --git a/third_party/WebKit/Source/core/paint/DeprecatedPaintLayerStackingNode.cpp b/third_party/WebKit/Source/core/paint/DeprecatedPaintLayerStackingNode.cpp
index d20cea4..b1fb9c5 100644
--- a/third_party/WebKit/Source/core/paint/DeprecatedPaintLayerStackingNode.cpp
+++ b/third_party/WebKit/Source/core/paint/DeprecatedPaintLayerStackingNode.cpp
@@ -44,7 +44,6 @@
 #include "config.h"
 #include "core/paint/DeprecatedPaintLayerStackingNode.h"
 
-#include "core/dom/Node.h"
 #include "core/layout/LayoutView.h"
 #include "core/layout/compositing/DeprecatedPaintLayerCompositor.h"
 #include "core/paint/DeprecatedPaintLayer.h"
@@ -55,8 +54,8 @@ namespace blink {
 // FIXME: This should not require DeprecatedPaintLayer. There is currently a cycle where
 // in order to determine if we shoulBeTreatedAsStackingContextForPainting() we have to ask the paint
 // layer about some of its state.
-DeprecatedPaintLayerStackingNode::DeprecatedPaintLayerStackingNode(LayoutBoxModelObject& layoutObject)
-    : m_layoutObject(layoutObject)
+DeprecatedPaintLayerStackingNode::DeprecatedPaintLayerStackingNode(DeprecatedPaintLayer* layer)
+    : m_layer(layer)
 #if ENABLE(ASSERT)
     , m_layerListMutationAllowed(true)
     , m_stackingParent(0)
@@ -72,7 +71,7 @@ DeprecatedPaintLayerStackingNode::DeprecatedPaintLayerStackingNode(LayoutBoxMode
 DeprecatedPaintLayerStackingNode::~DeprecatedPaintLayerStackingNode()
 {
 #if ENABLE(ASSERT)
-    if (!layoutObject().documentBeingDestroyed()) {
+    if (!layoutObject()->documentBeingDestroyed()) {
         ASSERT(!isInStackingParentZOrderLists());
 
         updateStackingParentForZOrderLists(0);
@@ -88,8 +87,8 @@ static inline bool compareZIndex(DeprecatedPaintLayerStackingNode* first, Deprec
 
 DeprecatedPaintLayerCompositor* DeprecatedPaintLayerStackingNode::compositor() const
 {
-    ASSERT(layoutObject().view());
-    return layoutObject().view()->compositor();
+    ASSERT(layoutObject()->view());
+    return layoutObject()->view()->compositor();
 }
 
 void DeprecatedPaintLayerStackingNode::dirtyZOrderLists()
@@ -107,7 +106,7 @@ void DeprecatedPaintLayerStackingNode::dirtyZOrderLists()
         m_negZOrderList->clear();
     m_zOrderListsDirty = true;
 
-    if (!layoutObject().documentBeingDestroyed())
+    if (!layoutObject()->documentBeingDestroyed())
         compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
 }
 
@@ -117,41 +116,14 @@ void DeprecatedPaintLayerStackingNode::dirtyStackingContextZOrderLists()
         stackingNode->dirtyZOrderLists();
 }
 
-static bool isInTopLayer(const LayoutObject& layoutObject)
-{
-    const Node* node = layoutObject.node();
-    return node && node->isElementNode() && toElement(node)->isInTopLayer();
-}
-
 void DeprecatedPaintLayerStackingNode::rebuildZOrderLists()
 {
     ASSERT(m_layerListMutationAllowed);
     ASSERT(isDirtyStackingContext());
 
-    for (LayoutObject* descendant = layoutObject().slowFirstChild(); descendant;) {
-        if (isInTopLayer(*descendant)) {
-            // Top layer objects are handled below.
-            descendant = descendant->nextInPreOrderAfterChildren(&layoutObject());
-            continue;
-        }
-
-        // FIXME: Some non-LayoutBoxModeObject can have position != static and thus would be treated like
-        // stacking context. However we can't store them in the lists unless they have a DeprecatedPaintLayer.
-        if (descendant->styleRef().isTreatedAsStackingContextForPainting() && descendant->hasLayer()) {
-            OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& buffer = (descendant->style()->zIndex() >= 0) ? m_posZOrderList : m_negZOrderList;
-            if (!buffer)
-                buffer = adoptPtr(new Vector<DeprecatedPaintLayerStackingNode*>);
-            buffer->append(toLayoutBoxModelObject(descendant)->layer()->stackingNode());
-        }
-
-        if (descendant->styleRef().isStackingContext()) {
-            // We found a stacking context, just continue walking the other subtrees.
-            // They will collect their own descendant stacking contexts.
-            descendant = descendant->nextInPreOrderAfterChildren(&layoutObject());
-        } else {
-            // Not stacking context, continue deeper.
-            descendant = descendant->nextInPreOrder(&layoutObject());
-        }
+    for (DeprecatedPaintLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
+        if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
+            child->stackingNode()->collectLayers(m_posZOrderList, m_negZOrderList);
     }
 
     // Sort the two lists.
@@ -161,19 +133,19 @@ void DeprecatedPaintLayerStackingNode::rebuildZOrderLists()
     if (m_negZOrderList)
         std::stable_sort(m_negZOrderList->begin(), m_negZOrderList->end(), compareZIndex);
 
-    // Append stacking contexts for top layer elements after normal layer collection, to ensure they are on top regardless of z-indexes.
+    // Append layers for top layer elements after normal layer collection, to ensure they are on top regardless of z-indexes.
     // The layoutObjects of top layer elements are children of the view, sorted in top layer stacking order.
-    if (layoutObject().isLayoutView()) {
-        LayoutView& view = toLayoutView(layoutObject());
-        for (LayoutObject* child = view.firstChild(); child; child = child->nextSibling()) {
-            if (!isInTopLayer(*child))
-                continue;
-
-            // Create the buffer if it doesn't exist yet.
-            if (!m_posZOrderList)
-                m_posZOrderList = adoptPtr(new Vector<DeprecatedPaintLayerStackingNode*>);
-            ASSERT(child->style()->isStackingContext());
-            m_posZOrderList->append(toLayoutBoxModelObject(child)->layer()->stackingNode());
+    if (layer()->isRootLayer()) {
+        LayoutView* view = layoutObject()->view();
+        for (LayoutObject* child = view->firstChild(); child; child = child->nextSibling()) {
+            Element* childElement = (child->node() && child->node()->isElementNode()) ? toElement(child->node()) : 0;
+            if (childElement && childElement->isInTopLayer()) {
+                DeprecatedPaintLayer* layer = toLayoutBoxModelObject(child)->layer();
+                // Create the buffer if it doesn't exist yet.
+                if (!m_posZOrderList)
+                    m_posZOrderList = adoptPtr(new Vector<DeprecatedPaintLayerStackingNode*>);
+                m_posZOrderList->append(layer->stackingNode());
+            }
         }
     }
 
@@ -184,6 +156,26 @@ void DeprecatedPaintLayerStackingNode::rebuildZOrderLists()
     m_zOrderListsDirty = false;
 }
 
+void DeprecatedPaintLayerStackingNode::collectLayers(OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& posBuffer, OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& negBuffer)
+{
+    if (layer()->isInTopLayer())
+        return;
+
+    if (isTreatedAsStackingContextForPainting()) {
+        OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& buffer = (zIndex() >= 0) ? posBuffer : negBuffer;
+        if (!buffer)
+            buffer = adoptPtr(new Vector<DeprecatedPaintLayerStackingNode*>);
+        buffer->append(this);
+    }
+
+    if (!isStackingContext()) {
+        for (DeprecatedPaintLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
+            if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
+                child->stackingNode()->collectLayers(posBuffer, negBuffer);
+        }
+    }
+}
+
 #if ENABLE(ASSERT)
 bool DeprecatedPaintLayerStackingNode::isInStackingParentZOrderLists() const
 {
@@ -249,7 +241,7 @@ void DeprecatedPaintLayerStackingNode::updateIsTreatedAsStackingContextForPainti
         return;
 
     m_isTreatedAsStackingContextForPainting = isTreatedAsStackingContextForPainting;
-    if (!layoutObject().documentBeingDestroyed() && !layer()->isRootLayer())
+    if (!layoutObject()->documentBeingDestroyed() && !layer()->isRootLayer())
         compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
     dirtyStackingContextZOrderLists();
 }
@@ -264,9 +256,9 @@ DeprecatedPaintLayerStackingNode* DeprecatedPaintLayerStackingNode::ancestorStac
     return 0;
 }
 
-DeprecatedPaintLayer* DeprecatedPaintLayerStackingNode::layer() const
+LayoutBoxModelObject* DeprecatedPaintLayerStackingNode::layoutObject() const
 {
-    return layoutObject().layer();
+    return m_layer->layoutObject();
 }
 
 } // namespace blink
diff --git a/third_party/WebKit/Source/core/paint/DeprecatedPaintLayerStackingNode.h b/third_party/WebKit/Source/core/paint/DeprecatedPaintLayerStackingNode.h
index c54e26e..022d989 100644
--- a/third_party/WebKit/Source/core/paint/DeprecatedPaintLayerStackingNode.h
+++ b/third_party/WebKit/Source/core/paint/DeprecatedPaintLayerStackingNode.h
@@ -61,12 +61,12 @@ class LayoutBoxModelObject;
 class CORE_EXPORT DeprecatedPaintLayerStackingNode {
     WTF_MAKE_NONCOPYABLE(DeprecatedPaintLayerStackingNode);
 public:
-    explicit DeprecatedPaintLayerStackingNode(LayoutBoxModelObject&);
+    explicit DeprecatedPaintLayerStackingNode(DeprecatedPaintLayer*);
     ~DeprecatedPaintLayerStackingNode();
 
-    int zIndex() const { return layoutObject().style()->zIndex(); }
+    int zIndex() const { return layoutObject()->style()->zIndex(); }
 
-    bool isStackingContext() const { return layoutObject().style()->isStackingContext(); }
+    bool isStackingContext() const { return layoutObject()->style()->isStackingContext(); }
 
     // Update our normal and z-index lists.
     void updateLayerListsIfNeeded();
@@ -87,9 +87,7 @@ public:
 
     DeprecatedPaintLayerStackingNode* ancestorStackingContextNode() const;
 
-    // FIXME: A lot of code depends on this function but shouldn't. We should
-    // build our code on top of LayoutBoxModelObject, not DeprecatedPaintLayer.
-    DeprecatedPaintLayer* layer() const;
+    DeprecatedPaintLayer* layer() const { return m_layer; }
 
 #if ENABLE(ASSERT)
     bool layerListMutationAllowed() const { return m_layerListMutationAllowed; }
@@ -116,6 +114,7 @@ private:
     }
 
     void rebuildZOrderLists();
+    void collectLayers(OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& posZOrderList, OwnPtr<Vector<DeprecatedPaintLayerStackingNode*>>& negZOrderList);
 
 #if ENABLE(ASSERT)
     bool isInStackingParentZOrderLists() const;
@@ -123,15 +122,15 @@ private:
     void setStackingParent(DeprecatedPaintLayerStackingNode* stackingParent) { m_stackingParent = stackingParent; }
 #endif
 
-    bool shouldBeTreatedAsStackingContextForPainting() const { return layoutObject().style()->isTreatedAsStackingContextForPainting(); }
+    bool shouldBeTreatedAsStackingContextForPainting() const { return layoutObject()->style()->isTreatedAsStackingContextForPainting(); }
 
     bool isDirtyStackingContext() const { return m_zOrderListsDirty && isStackingContext(); }
 
     DeprecatedPaintLayerCompositor* compositor() const;
     // We can't return a LayoutBox as LayoutInline can be a stacking context.
-    LayoutBoxModelObject& layoutObject() const { return m_layoutObject; }
+    LayoutBoxModelObject* layoutObject() const;
 
-    LayoutBoxModelObject& m_layoutObject;
+    DeprecatedPaintLayer* m_layer;
 
     // m_posZOrderList holds a sorted list of all the descendant nodes within
     // that have z-indices of 0 or greater (auto will count as 0).