1 files changed, 52 insertions, 382 deletions

diff --git a/chromium/third_party/WebKit/Source/core/rendering/RenderLayerStackingNode.cpp b/chromium/third_party/WebKit/Source/core/rendering/RenderLayerStackingNode.cpp
index 715dcecfe77..eaa6dfc09b4 100644
--- a/chromium/third_party/WebKit/Source/core/rendering/RenderLayerStackingNode.cpp
+++ b/chromium/third_party/WebKit/Source/core/rendering/RenderLayerStackingNode.cpp
@@ -45,37 +45,33 @@
 #include "core/rendering/RenderLayerStackingNode.h"
 
 #include "core/rendering/RenderLayer.h"
-#include "core/rendering/RenderLayerCompositor.h"
 #include "core/rendering/RenderView.h"
+#include "core/rendering/compositing/RenderLayerCompositor.h"
 #include "public/platform/Platform.h"
 
 namespace WebCore {
 
 // FIXME: This should not require RenderLayer. There is currently a cycle where
-// in order to determine if we shoulBeNormalFlowOnly() and isStackingContainer()
-// we have to ask the render layer about some of its state.
+// in order to determine if we shoulBeNormalFlowOnly() we have to ask the render
+// layer about some of its state.
 RenderLayerStackingNode::RenderLayerStackingNode(RenderLayer* layer)
     : m_layer(layer)
-    , m_descendantsAreContiguousInStackingOrder(false)
-    , m_descendantsAreContiguousInStackingOrderDirty(true)
     , m_normalFlowListDirty(true)
-    , m_needsToBeStackingContainer(false)
-    , m_needsToBeStackingContainerHasBeenRecorded(false)
-#if !ASSERT_DISABLED
+#if ASSERT_ENABLED
     , m_layerListMutationAllowed(true)
     , m_stackingParent(0)
 #endif
 {
     m_isNormalFlowOnly = shouldBeNormalFlowOnly();
 
-    // Non-stacking containers should have empty z-order lists. As this is already the case,
+    // Non-stacking contexts should have empty z-order lists. As this is already the case,
     // there is no need to dirty / recompute these lists.
-    m_zOrderListsDirty = isStackingContainer();
+    m_zOrderListsDirty = isStackingContext();
 }
 
 RenderLayerStackingNode::~RenderLayerStackingNode()
 {
-#if !ASSERT_DISABLED
+#if ASSERT_ENABLED
     if (!renderer()->documentBeingDestroyed()) {
         ASSERT(!isInStackingParentZOrderLists());
         ASSERT(!isInStackingParentNormalFlowList());
@@ -86,11 +82,6 @@ RenderLayerStackingNode::~RenderLayerStackingNode()
 #endif
 }
 
-bool RenderLayerStackingNode::isStackingContext(const RenderStyle* style) const
-{
-    return !style->hasAutoZIndex() || layer()->isRootLayer();
-}
-
 // Helper for the sorting of layers by z-index.
 static inline bool compareZIndex(RenderLayerStackingNode* first, RenderLayerStackingNode* second)
 {
@@ -99,47 +90,16 @@ static inline bool compareZIndex(RenderLayerStackingNode* first, RenderLayerStac
 
 RenderLayerCompositor* RenderLayerStackingNode::compositor() const
 {
-    if (!renderer()->view())
-        return 0;
+    ASSERT(renderer()->view());
     return renderer()->view()->compositor();
 }
 
-void RenderLayerStackingNode::dirtyNormalFlowListCanBePromotedToStackingContainer()
-{
-    m_descendantsAreContiguousInStackingOrderDirty = true;
-
-    if (m_normalFlowListDirty || !normalFlowList())
-        return;
-
-    for (size_t index = 0; index < normalFlowList()->size(); ++index)
-        normalFlowList()->at(index)->dirtyNormalFlowListCanBePromotedToStackingContainer();
-}
-
-void RenderLayerStackingNode::dirtySiblingStackingNodeCanBePromotedToStackingContainer()
-{
-    RenderLayerStackingNode* stackingNode = ancestorStackingNode();
-    if (!stackingNode)
-        return;
-
-    if (!stackingNode->zOrderListsDirty() && stackingNode->posZOrderList()) {
-        for (size_t index = 0; index < stackingNode->posZOrderList()->size(); ++index)
-            stackingNode->posZOrderList()->at(index)->setDescendantsAreContiguousInStackingOrderDirty(true);
-    }
-
-    stackingNode->dirtyNormalFlowListCanBePromotedToStackingContainer();
-
-    if (!stackingNode->zOrderListsDirty() && stackingNode->negZOrderList()) {
-        for (size_t index = 0; index < stackingNode->negZOrderList()->size(); ++index)
-            stackingNode->negZOrderList()->at(index)->setDescendantsAreContiguousInStackingOrderDirty(true);
-    }
-}
-
 void RenderLayerStackingNode::dirtyZOrderLists()
 {
     ASSERT(m_layerListMutationAllowed);
-    ASSERT(isStackingContainer());
+    ASSERT(isStackingContext());
 
-#if !ASSERT_DISABLED
+#if ASSERT_ENABLED
     updateStackingParentForZOrderLists(0);
 #endif
 
@@ -149,35 +109,13 @@ void RenderLayerStackingNode::dirtyZOrderLists()
         m_negZOrderList->clear();
     m_zOrderListsDirty = true;
 
-    m_descendantsAreContiguousInStackingOrderDirty = true;
-
-    if (!renderer()->documentBeingDestroyed()) {
-        compositor()->setNeedsUpdateCompositingRequirementsState();
-        compositor()->setCompositingLayersNeedRebuild();
-        if (layer()->acceleratedCompositingForOverflowScrollEnabled())
-            compositor()->setNeedsToRecomputeCompositingRequirements();
-    }
+    if (!renderer()->documentBeingDestroyed())
+        compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
 }
 
-void RenderLayerStackingNode::dirtyStackingContainerZOrderLists()
+void RenderLayerStackingNode::dirtyStackingContextZOrderLists()
 {
-    // Any siblings in the ancestor stacking context could also be affected.
-    // Changing z-index, for example, could cause us to stack in between a
-    // sibling's descendants, meaning that we have to recompute
-    // m_descendantsAreContiguousInStackingOrder for that sibling.
-    dirtySiblingStackingNodeCanBePromotedToStackingContainer();
-
-    RenderLayerStackingNode* stackingContainerNode = ancestorStackingContainerNode();
-    if (stackingContainerNode)
-        stackingContainerNode->dirtyZOrderLists();
-
-    // Any change that could affect our stacking container's z-order list could
-    // cause other RenderLayers in our stacking context to either opt in or out
-    // of composited scrolling. It is important that we make our stacking
-    // context aware of these z-order changes so the appropriate updating can
-    // happen.
-    RenderLayerStackingNode* stackingNode = ancestorStackingNode();
-    if (stackingNode && stackingNode != stackingContainerNode)
+    if (RenderLayerStackingNode* stackingNode = ancestorStackingContextNode())
         stackingNode->dirtyZOrderLists();
 }
 
@@ -185,7 +123,7 @@ void RenderLayerStackingNode::dirtyNormalFlowList()
 {
     ASSERT(m_layerListMutationAllowed);
 
-#if !ASSERT_DISABLED
+#if ASSERT_ENABLED
     updateStackingParentForNormalFlowList(0);
 #endif
 
@@ -193,57 +131,48 @@ void RenderLayerStackingNode::dirtyNormalFlowList()
         m_normalFlowList->clear();
     m_normalFlowListDirty = true;
 
-    if (!renderer()->documentBeingDestroyed()) {
-        compositor()->setCompositingLayersNeedRebuild();
-        if (layer()->acceleratedCompositingForOverflowScrollEnabled())
-            compositor()->setNeedsToRecomputeCompositingRequirements();
-    }
+    if (!renderer()->documentBeingDestroyed())
+        compositor()->setNeedsCompositingUpdate(CompositingUpdateRebuildTree);
 }
 
 void RenderLayerStackingNode::rebuildZOrderLists()
 {
     ASSERT(m_layerListMutationAllowed);
-    ASSERT(isDirtyStackingContainer());
-    rebuildZOrderLists(m_posZOrderList, m_negZOrderList);
-
-#if !ASSERT_DISABLED
-    updateStackingParentForZOrderLists(this);
-#endif
-
-    m_zOrderListsDirty = false;
-}
+    ASSERT(isDirtyStackingContext());
 
-void RenderLayerStackingNode::rebuildZOrderLists(OwnPtr<Vector<RenderLayerStackingNode*> >& posZOrderList,
-    OwnPtr<Vector<RenderLayerStackingNode*> >& negZOrderList, const RenderLayerStackingNode* nodeToForceAsStackingContainer,
-    CollectLayersBehavior collectLayersBehavior)
-{
     for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
         if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
-            child->stackingNode()->collectLayers(posZOrderList, negZOrderList, nodeToForceAsStackingContainer, collectLayersBehavior);
+            child->stackingNode()->collectLayers(m_posZOrderList, m_negZOrderList);
     }
 
     // Sort the two lists.
-    if (posZOrderList)
-        std::stable_sort(posZOrderList->begin(), posZOrderList->end(), compareZIndex);
+    if (m_posZOrderList)
+        std::stable_sort(m_posZOrderList->begin(), m_posZOrderList->end(), compareZIndex);
 
-    if (negZOrderList)
-        std::stable_sort(negZOrderList->begin(), negZOrderList->end(), compareZIndex);
+    if (m_negZOrderList)
+        std::stable_sort(m_negZOrderList->begin(), m_negZOrderList->end(), compareZIndex);
 
     // Append layers for top layer elements after normal layer collection, to ensure they are on top regardless of z-indexes.
     // The renderers of top layer elements are children of the view, sorted in top layer stacking order.
     if (layer()->isRootLayer()) {
-        RenderObject* view = renderer()->view();
+        RenderView* view = renderer()->view();
         for (RenderObject* child = view->firstChild(); child; child = child->nextSibling()) {
             Element* childElement = (child->node() && child->node()->isElementNode()) ? toElement(child->node()) : 0;
             if (childElement && childElement->isInTopLayer()) {
                 RenderLayer* layer = toRenderLayerModelObject(child)->layer();
                 // Create the buffer if it doesn't exist yet.
-                if (!posZOrderList)
-                    posZOrderList = adoptPtr(new Vector<RenderLayerStackingNode*>);
-                posZOrderList->append(layer->stackingNode());
+                if (!m_posZOrderList)
+                    m_posZOrderList = adoptPtr(new Vector<RenderLayerStackingNode*>);
+                m_posZOrderList->append(layer->stackingNode());
             }
         }
     }
+
+#if ASSERT_ENABLED
+    updateStackingParentForZOrderLists(this);
+#endif
+
+    m_zOrderListsDirty = false;
 }
 
 void RenderLayerStackingNode::updateNormalFlowList()
@@ -254,7 +183,6 @@ void RenderLayerStackingNode::updateNormalFlowList()
     ASSERT(m_layerListMutationAllowed);
 
     for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
-        // Ignore non-overflow layers and reflections.
         if (child->stackingNode()->isNormalFlowOnly() && (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)) {
             if (!m_normalFlowList)
                 m_normalFlowList = adoptPtr(new Vector<RenderLayerStackingNode*>);
@@ -262,71 +190,36 @@ void RenderLayerStackingNode::updateNormalFlowList()
         }
     }
 
-#if !ASSERT_DISABLED
+#if ASSERT_ENABLED
     updateStackingParentForNormalFlowList(this);
 #endif
 
     m_normalFlowListDirty = false;
 }
 
-void RenderLayerStackingNode::collectLayers(OwnPtr<Vector<RenderLayerStackingNode*> >& posBuffer, OwnPtr<Vector<RenderLayerStackingNode*> >& negBuffer,
-    const RenderLayerStackingNode* nodeToForceAsStackingContainer, CollectLayersBehavior collectLayersBehavior)
+void RenderLayerStackingNode::collectLayers(OwnPtr<Vector<RenderLayerStackingNode*> >& posBuffer, OwnPtr<Vector<RenderLayerStackingNode*> >& negBuffer)
 {
     if (layer()->isInTopLayer())
         return;
 
     layer()->updateDescendantDependentFlags();
 
-    bool isStacking = false;
-    bool isNormalFlow = false;
-
-    switch (collectLayersBehavior) {
-    case ForceLayerToStackingContainer:
-        ASSERT(nodeToForceAsStackingContainer);
-        if (this == nodeToForceAsStackingContainer) {
-            isStacking = true;
-            isNormalFlow = false;
-        } else {
-            isStacking = isStackingContext();
-            isNormalFlow = shouldBeNormalFlowOnlyIgnoringCompositedScrolling();
-        }
-        break;
-    case OverflowScrollCanBeStackingContainers:
-        ASSERT(!nodeToForceAsStackingContainer);
-        isStacking = isStackingContainer();
-        isNormalFlow = isNormalFlowOnly();
-        break;
-    case OnlyStackingContextsCanBeStackingContainers:
-        isStacking = isStackingContext();
-        isNormalFlow = shouldBeNormalFlowOnlyIgnoringCompositedScrolling();
-        break;
-    }
-
-    // Overflow layers are just painted by their enclosing layers, so they don't get put in zorder lists.
-    if (!isNormalFlow && !layer()->isOutOfFlowRenderFlowThread()) {
-        // Determine which buffer the child should be in.
+    if (!isNormalFlowOnly()) {
         OwnPtr<Vector<RenderLayerStackingNode*> >& buffer = (zIndex() >= 0) ? posBuffer : negBuffer;
-
-        // Create the buffer if it doesn't exist yet.
         if (!buffer)
             buffer = adoptPtr(new Vector<RenderLayerStackingNode*>);
-
-        // Append ourselves at the end of the appropriate buffer.
         buffer->append(this);
     }
 
-    // Recur into our children to collect more layers, but only if we don't establish
-    // a stacking context/container.
-    if (!isStacking) {
+    if (!isStackingContext()) {
         for (RenderLayer* child = layer()->firstChild(); child; child = child->nextSibling()) {
-            // Ignore reflections.
             if (!layer()->reflectionInfo() || layer()->reflectionInfo()->reflectionLayer() != child)
-                child->stackingNode()->collectLayers(posBuffer, negBuffer, nodeToForceAsStackingContainer, collectLayersBehavior);
+                child->stackingNode()->collectLayers(posBuffer, negBuffer);
         }
     }
 }
 
-#if !ASSERT_DISABLED
+#if ASSERT_ENABLED
 bool RenderLayerStackingNode::isInStackingParentZOrderLists() const
 {
     if (!m_stackingParent || m_stackingParent->zOrderListsDirty())
@@ -386,50 +279,26 @@ void RenderLayerStackingNode::updateLayerListsIfNeeded()
 
 void RenderLayerStackingNode::updateStackingNodesAfterStyleChange(const RenderStyle* oldStyle)
 {
-    bool wasStackingContext = oldStyle ? isStackingContext(oldStyle) : false;
-    EVisibility oldVisibility = oldStyle ? oldStyle->visibility() : VISIBLE;
+    bool wasStackingContext = oldStyle ? !oldStyle->hasAutoZIndex() : false;
     int oldZIndex = oldStyle ? oldStyle->zIndex() : 0;
 
-    // FIXME: RenderLayer already handles visibility changes through our visiblity dirty bits. This logic could
-    // likely be folded along with the rest.
     bool isStackingContext = this->isStackingContext();
-    if (isStackingContext == wasStackingContext && oldVisibility == renderer()->style()->visibility() && oldZIndex == zIndex())
+    if (isStackingContext == wasStackingContext && oldZIndex == zIndex())
         return;
 
-    dirtyStackingContainerZOrderLists();
+    dirtyStackingContextZOrderLists();
 
-    if (isStackingContainer())
+    if (isStackingContext)
         dirtyZOrderLists();
     else
         clearZOrderLists();
-
-    compositor()->setNeedsUpdateCompositingRequirementsState();
 }
 
+// FIXME: Rename shouldBeNormalFlowOnly to something more accurate now that CSS
+// 2.1 defines the term "normal flow".
 bool RenderLayerStackingNode::shouldBeNormalFlowOnly() const
 {
-    return shouldBeNormalFlowOnlyIgnoringCompositedScrolling() && !layer()->needsCompositedScrolling();
-}
-
-bool RenderLayerStackingNode::shouldBeNormalFlowOnlyIgnoringCompositedScrolling() const
-{
-    const bool couldBeNormalFlow = renderer()->hasOverflowClip()
-        || renderer()->hasReflection()
-        || renderer()->hasMask()
-        || renderer()->isCanvas()
-        || renderer()->isVideo()
-        || renderer()->isEmbeddedObject()
-        || renderer()->isRenderIFrame()
-        || (renderer()->style()->specifiesColumns() && !layer()->isRootLayer());
-    const bool preventsElementFromBeingNormalFlow = renderer()->isPositioned()
-        || renderer()->hasTransform()
-        || renderer()->hasClipPath()
-        || renderer()->hasFilter()
-        || renderer()->hasBlendMode()
-        || layer()->isTransparent()
-        || renderer()->style()->hasFlowFrom();
-
-    return couldBeNormalFlow && !preventsElementFromBeingNormalFlow;
+    return !isStackingContext() && !renderer()->isPositioned();
 }
 
 void RenderLayerStackingNode::updateIsNormalFlowOnly()
@@ -441,215 +310,16 @@ void RenderLayerStackingNode::updateIsNormalFlowOnly()
     m_isNormalFlowOnly = isNormalFlowOnly;
     if (RenderLayer* p = layer()->parent())
         p->stackingNode()->dirtyNormalFlowList();
-    dirtyStackingContainerZOrderLists();
-}
-
-bool RenderLayerStackingNode::needsToBeStackingContainer() const
-{
-    return layer()->scrollableArea() && layer()->scrollableArea()->adjustForForceCompositedScrollingMode(m_needsToBeStackingContainer);
-}
-
-// Determine whether the current layer can be promoted to a stacking container.
-// We do this by computing what positive and negative z-order lists would look
-// like before and after promotion, and ensuring that proper stacking order is
-// preserved between the two sets of lists.
-void RenderLayerStackingNode::updateDescendantsAreContiguousInStackingOrder()
-{
-    TRACE_EVENT0("blink_rendering,comp-scroll", "RenderLayerStackingNode::updateDescendantsAreContiguousInStackingOrder");
-
-    const RenderLayer* currentLayer = layer();
-    if (isStackingContext() || !m_descendantsAreContiguousInStackingOrderDirty || !currentLayer->acceleratedCompositingForOverflowScrollEnabled())
-        return;
-
-    if (!currentLayer->scrollsOverflow())
-        return;
-
-    RenderLayerStackingNode* stackingNode = ancestorStackingNode();
-    if (!stackingNode)
-        return;
-
-    OwnPtr<Vector<RenderLayerStackingNode*> > posZOrderListBeforePromote = adoptPtr(new Vector<RenderLayerStackingNode*>);
-    OwnPtr<Vector<RenderLayerStackingNode*> > negZOrderListBeforePromote = adoptPtr(new Vector<RenderLayerStackingNode*>);
-    OwnPtr<Vector<RenderLayerStackingNode*> > posZOrderListAfterPromote = adoptPtr(new Vector<RenderLayerStackingNode*>);
-    OwnPtr<Vector<RenderLayerStackingNode*> > negZOrderListAfterPromote = adoptPtr(new Vector<RenderLayerStackingNode*>);
-
-    collectBeforePromotionZOrderList(stackingNode, posZOrderListBeforePromote, negZOrderListBeforePromote);
-    collectAfterPromotionZOrderList(stackingNode, posZOrderListAfterPromote, negZOrderListAfterPromote);
-
-    size_t maxIndex = std::min(posZOrderListAfterPromote->size() + negZOrderListAfterPromote->size(), posZOrderListBeforePromote->size() + negZOrderListBeforePromote->size());
-
-    m_descendantsAreContiguousInStackingOrderDirty = false;
-    m_descendantsAreContiguousInStackingOrder = false;
-
-    const RenderLayerStackingNode* nodeAfterPromote = 0;
-    for (size_t i = 0; i < maxIndex && nodeAfterPromote != this; ++i) {
-        const RenderLayerStackingNode* nodeBeforePromote = i < negZOrderListBeforePromote->size()
-            ? negZOrderListBeforePromote->at(i)
-            : posZOrderListBeforePromote->at(i - negZOrderListBeforePromote->size());
-        nodeAfterPromote = i < negZOrderListAfterPromote->size()
-            ? negZOrderListAfterPromote->at(i)
-            : posZOrderListAfterPromote->at(i - negZOrderListAfterPromote->size());
-
-        if (nodeBeforePromote != nodeAfterPromote && (nodeAfterPromote != this || renderer()->hasBackground()))
-            return;
-    }
-
-    nodeAfterPromote = 0;
-    for (size_t i = 0; i < maxIndex && nodeAfterPromote != this; ++i) {
-        const RenderLayerStackingNode* nodeBeforePromote = i < posZOrderListBeforePromote->size()
-            ? posZOrderListBeforePromote->at(posZOrderListBeforePromote->size() - i - 1)
-            : negZOrderListBeforePromote->at(negZOrderListBeforePromote->size() + posZOrderListBeforePromote->size() - i - 1);
-        nodeAfterPromote = i < posZOrderListAfterPromote->size()
-            ? posZOrderListAfterPromote->at(posZOrderListAfterPromote->size() - i - 1)
-            : negZOrderListAfterPromote->at(negZOrderListAfterPromote->size() + posZOrderListAfterPromote->size() - i - 1);
-
-        if (nodeBeforePromote != nodeAfterPromote && nodeAfterPromote != this)
-            return;
-    }
-
-    m_descendantsAreContiguousInStackingOrder = true;
-}
-
-void RenderLayerStackingNode::collectBeforePromotionZOrderList(RenderLayerStackingNode* ancestorStackingNode,
-    OwnPtr<Vector<RenderLayerStackingNode*> >& posZOrderList, OwnPtr<Vector<RenderLayerStackingNode*> >& negZOrderList)
-{
-    ancestorStackingNode->rebuildZOrderLists(posZOrderList, negZOrderList, this, OnlyStackingContextsCanBeStackingContainers);
-
-    const RenderLayer* currentLayer = layer();
-    const RenderLayer* positionedAncestor = currentLayer->parent();
-    while (positionedAncestor && !positionedAncestor->isPositionedContainer() && !positionedAncestor->stackingNode()->isStackingContext())
-        positionedAncestor = positionedAncestor->parent();
-    if (positionedAncestor && (!positionedAncestor->isPositionedContainer() || positionedAncestor->stackingNode()->isStackingContext()))
-        positionedAncestor = 0;
-
-    if (!posZOrderList)
-        posZOrderList = adoptPtr(new Vector<RenderLayerStackingNode*>());
-    else if (posZOrderList->find(this) != kNotFound)
-        return;
-
-    // The current node will appear in the z-order lists after promotion, so
-    // for a meaningful comparison, we must insert it in the z-order lists
-    // before promotion if it does not appear there already.
-    if (!positionedAncestor) {
-        posZOrderList->prepend(this);
-        return;
-    }
-
-    for (size_t index = 0; index < posZOrderList->size(); index++) {
-        if (posZOrderList->at(index)->layer() == positionedAncestor) {
-            posZOrderList->insert(index + 1, this);
-            return;
-        }
-    }
-}
-
-void RenderLayerStackingNode::collectAfterPromotionZOrderList(RenderLayerStackingNode* ancestorStackingNode,
-    OwnPtr<Vector<RenderLayerStackingNode*> >& posZOrderList, OwnPtr<Vector<RenderLayerStackingNode*> >& negZOrderList)
-{
-    ancestorStackingNode->rebuildZOrderLists(posZOrderList, negZOrderList, this, ForceLayerToStackingContainer);
+    dirtyStackingContextZOrderLists();
 }
 
-// Compute what positive and negative z-order lists would look like before and
-// after promotion, so we can later ensure that proper stacking order is
-// preserved between the two sets of lists.
-//
-// A few examples:
-// c = currentLayer
-// - = negative z-order child of currentLayer
-// + = positive z-order child of currentLayer
-// a = positioned ancestor of currentLayer
-// x = any other RenderLayer in the list
-//
-// (a) xxxxx-----++a+++x
-// (b) xxx-----c++++++xx
-//
-// Normally the current layer would be painted in the normal flow list if it
-// doesn't already appear in the positive z-order list. However, in the case
-// that the layer has a positioned ancestor, it will paint directly after the
-// positioned ancestor. In example (a), the current layer would be painted in
-// the middle of its own positive z-order children, so promoting would cause a
-// change in paint order (since a promoted layer will paint all of its positive
-// z-order children strictly after it paints itself).
-//
-// In example (b), it is ok to promote the current layer only if it does not
-// have a background. If it has a background, the background gets painted before
-// the layer's negative z-order children, so again, a promotion would cause a
-// change in paint order (causing the background to get painted after the
-// negative z-order children instead of before).
-//
-void RenderLayerStackingNode::computePaintOrderList(PaintOrderListType type, Vector<RefPtr<Node> >& list)
+RenderLayerStackingNode* RenderLayerStackingNode::ancestorStackingContextNode() const
 {
-    OwnPtr<Vector<RenderLayerStackingNode*> > posZOrderList;
-    OwnPtr<Vector<RenderLayerStackingNode*> > negZOrderList;
-
-    RenderLayerStackingNode* stackingNode = ancestorStackingNode();
-    if (!stackingNode)
-        return;
-
-    switch (type) {
-    case BeforePromote:
-        collectBeforePromotionZOrderList(stackingNode, posZOrderList, negZOrderList);
-        break;
-    case AfterPromote:
-        collectAfterPromotionZOrderList(stackingNode, posZOrderList, negZOrderList);
-        break;
-    }
-
-    if (negZOrderList) {
-        for (size_t index = 0; index < negZOrderList->size(); ++index)
-            list.append(negZOrderList->at(index)->renderer()->node());
-    }
-
-    if (posZOrderList) {
-        for (size_t index = 0; index < posZOrderList->size(); ++index)
-            list.append(posZOrderList->at(index)->renderer()->node());
+    for (RenderLayer* ancestor = layer()->parent(); ancestor; ancestor = ancestor->parent()) {
+        RenderLayerStackingNode* stackingNode = ancestor->stackingNode();
+        if (stackingNode->isStackingContext())
+            return stackingNode;
     }
-}
-
-bool RenderLayerStackingNode::descendantsAreContiguousInStackingOrder() const
-{
-    if (isStackingContext() || !ancestorStackingContainerNode())
-        return true;
-
-    ASSERT(!m_descendantsAreContiguousInStackingOrderDirty);
-    return m_descendantsAreContiguousInStackingOrder;
-}
-
-bool RenderLayerStackingNode::setNeedsToBeStackingContainer(bool needsToBeStackingContainer)
-{
-    if (this->needsToBeStackingContainer() == needsToBeStackingContainer)
-        return false;
-
-    // Count the total number of RenderLayers which need to be stacking
-    // containers some point. This should be recorded at most once per
-    // RenderLayer, so we check m_needsToBeStackingContainerHasBeenRecorded.
-    if (layer()->acceleratedCompositingForOverflowScrollEnabled() && !m_needsToBeStackingContainerHasBeenRecorded) {
-        blink::Platform::current()->histogramEnumeration("Renderer.CompositedScrolling", RenderLayer::NeedsToBeStackingContainerBucket, RenderLayer::CompositedScrollingHistogramMax);
-        m_needsToBeStackingContainerHasBeenRecorded = true;
-    }
-
-    m_needsToBeStackingContainer = needsToBeStackingContainer;
-
-    return true;
-}
-
-RenderLayerStackingNode* RenderLayerStackingNode::ancestorStackingContainerNode() const
-{
-    RenderLayer* ancestor = layer()->parent();
-    while (ancestor && !ancestor->stackingNode()->isStackingContainer())
-        ancestor = ancestor->parent();
-    if (ancestor)
-        return ancestor->stackingNode();
-    return 0;
-}
-
-RenderLayerStackingNode* RenderLayerStackingNode::ancestorStackingNode() const
-{
-    RenderLayer* ancestor = layer()->parent();
-    while (ancestor && !ancestor->stackingNode()->isStackingContext())
-        ancestor = ancestor->parent();
-    if (ancestor)
-        return ancestor->stackingNode();
     return 0;
 }