Generate scroll/clip display item hierarchy for SPv2

Source/core/paint/DeprecatedPaintLayer.cpp

Index: Source/core/paint/DeprecatedPaintLayer.cpp
diff --git a/Source/core/paint/DeprecatedPaintLayer.cpp b/Source/core/paint/DeprecatedPaintLayer.cpp
index 561020b810667e0304e8f6c13af08d4f3a715cec..930d82e1f41faf38494796518af146967a59a707 100644
--- a/Source/core/paint/DeprecatedPaintLayer.cpp
+++ b/Source/core/paint/DeprecatedPaintLayer.cpp
@@ -711,6 +711,19 @@ bool DeprecatedPaintLayer::update3DTransformedDescendantStatus()
     return has3DTransform();
 }
 
+LayoutPoint DeprecatedPaintLayer::locationExcludeOverflowScroll() const
+{
+    // Our m_location already has scroll offset baked-in. We have to revert it here.

[pdr., 2015/09/08 04:23:53]

Ok, lets keep this and LocationQueryBehavior bug lets ASSERT(spv2) here to keep
other folks from making a mistake and using this too early.

[trchen, 2015/09/15 04:48:40]

Done.

+    IntSize scrollOffset;
+    if (DeprecatedPaintLayer* positionedParent = layoutObject()->isOutOfFlowPositioned() ? enclosingPositionedAncestor() : nullptr) {

[pdr., 2015/09/08 04:23:53]

Nit: temporary code, but can we rewrite it like so?
LayoutPoint DeprecatedPaintLayer::locationExcludeOverflowScroll() const
{
    ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());

    // Our m_location already has scroll offset baked-in. We have to revert it
here.
    DeprecatedPaintLayer* scrollParent = layoutObject()->isOutOfFlowPositioned()
? enclosingPositionedAncestor() : parent();
    if (scrollParent && scrollParent->layoutObject()->hasOverflowClip())
        return m_location +
LayoutSize(scrollParent->layoutBox()->scrolledContentOffset())
    return m_location;
}

[trchen, 2015/09/15 04:48:40]

Done.

+        if (positionedParent->layoutObject()->hasOverflowClip())
+            scrollOffset = positionedParent->layoutBox()->scrolledContentOffset();
+    } else if (parent() && parent()->layoutObject()->hasOverflowClip()) {
+        scrollOffset = parent()->layoutBox()->scrolledContentOffset();
+    }
+    return m_location + LayoutSize(scrollOffset);
+}
+
 bool DeprecatedPaintLayer::updateLayerPosition()
 {
     LayoutPoint localPoint;
@@ -1244,7 +1257,7 @@ void DeprecatedPaintLayer::insertOnlyThisLayer()
 }
 
 // Returns the layer reached on the walk up towards the ancestor.
-static inline const DeprecatedPaintLayer* accumulateOffsetTowardsAncestor(const DeprecatedPaintLayer* layer, const DeprecatedPaintLayer* ancestorLayer, LayoutPoint& location)
+static inline const DeprecatedPaintLayer* accumulateOffsetTowardsAncestor(const DeprecatedPaintLayer* layer, const DeprecatedPaintLayer* ancestorLayer, LayoutPoint& location, DeprecatedPaintLayer::LocationQueryBehavior behavior)
 {
     ASSERT(ancestorLayer != layer);
 
@@ -1269,10 +1282,10 @@ static inline const DeprecatedPaintLayer* accumulateOffsetTowardsAncestor(const
             // of both relative to the container and subtract.
 
             LayoutPoint thisCoords;
-            layer->convertToLayerCoords(parentLayer, thisCoords);
+            layer->convertToLayerCoords(parentLayer, thisCoords, behavior);
 
             LayoutPoint ancestorCoords;
-            ancestorLayer->convertToLayerCoords(parentLayer, ancestorCoords);
+            ancestorLayer->convertToLayerCoords(parentLayer, ancestorCoords, behavior);
 
             location += (thisCoords - ancestorCoords);
             return ancestorLayer;
@@ -1289,18 +1302,18 @@ static inline const DeprecatedPaintLayer* accumulateOffsetTowardsAncestor(const
     if (!parentLayer)
         return nullptr;
 
-    location += layer->location();
+    location += layer->location(behavior);
     return parentLayer;
 }
 
-void DeprecatedPaintLayer::convertToLayerCoords(const DeprecatedPaintLayer* ancestorLayer, LayoutPoint& location) const
+void DeprecatedPaintLayer::convertToLayerCoords(const DeprecatedPaintLayer* ancestorLayer, LayoutPoint& location, LocationQueryBehavior behavior) const
 {
     if (ancestorLayer == this)
         return;
 
     const DeprecatedPaintLayer* currLayer = this;
     while (currLayer && currLayer != ancestorLayer)
-        currLayer = accumulateOffsetTowardsAncestor(currLayer, ancestorLayer, location);
+        currLayer = accumulateOffsetTowardsAncestor(currLayer, ancestorLayer, location, behavior);
 }
 
 void DeprecatedPaintLayer::convertToLayerCoords(const DeprecatedPaintLayer* ancestorLayer, LayoutRect& rect) const
@@ -2333,6 +2346,9 @@ bool DeprecatedPaintLayer::hasCompositedClippingMask() const
 
 bool DeprecatedPaintLayer::paintsWithTransform(GlobalPaintFlags globalPaintFlags) const
 {
+    if (RuntimeEnabledFeatures::slimmingPaintV2Enabled())
+        return hasTransformRelatedProperty();
+
     return (transform() || layoutObject()->style()->position() == FixedPosition) && ((globalPaintFlags & GlobalPaintFlattenCompositingLayers) || compositingState() != PaintsIntoOwnBacking);
 }