Generate scroll/clip display item hierarchy for SPv2

Source/core/paint/LayerClipRecorder.cpp

Index: Source/core/paint/LayerClipRecorder.cpp
diff --git a/Source/core/paint/LayerClipRecorder.cpp b/Source/core/paint/LayerClipRecorder.cpp
index 748999d616ee5be0b64ce38d9cd791740081ea58..cc24eb0aa167135254bf3844e0bd1196245067f1 100644
--- a/Source/core/paint/LayerClipRecorder.cpp
+++ b/Source/core/paint/LayerClipRecorder.cpp
@@ -39,6 +39,28 @@ LayerClipRecorder::LayerClipRecorder(GraphicsContext& graphicsContext, const Lay
     }
 }
 
+LayerClipRecorder::LayerClipRecorder(GraphicsContext& context, const LayoutBox& layoutBox, const LayoutPoint& paintOffset)
+    : m_graphicsContext(context)
+    , m_layoutObject(layoutBox)
+    , m_clipType(DisplayItem::ClipDescendantStackingContext)
+{
+    ASSERT(layoutBox.hasOverflowClip());

[pdr., 2015/09/03 06:16:59]

Can you assert spv2 here?
ASSERT(RuntimeEnabledFeatures::slimmingPaintV2Enabled());

Similarly, in the other constructor can you assert that spv2 is not enabled?

[trchen, 2015/09/04 06:10:15]

Done.

+
+    LayoutRect clipRect = layoutBox.overflowClipRect(paintOffset);
+    Vector<FloatRoundedRect> roundedRects;
+    if (layoutBox.style()->hasBorderRadius())
+        roundedRects.append(layoutBox.style()->getRoundedInnerBorderFor(LayoutRect(paintOffset, layoutBox.size())));
+
+    if (RuntimeEnabledFeatures::slimmingPaintEnabled()) {
+        if (m_graphicsContext.displayItemList()->displayItemConstructionIsDisabled())
+            return;
+        m_graphicsContext.displayItemList()->createAndAppend<ClipDisplayItem>(m_layoutObject, m_clipType, pixelSnappedIntRect(clipRect), roundedRects);
+    } else {
+        ClipDisplayItem clipDisplayItem(m_layoutObject, m_clipType, pixelSnappedIntRect(clipRect), roundedRects);
+        clipDisplayItem.replay(m_graphicsContext);
+    }
+}
+
 static bool inContainingBlockChain(DeprecatedPaintLayer* startLayer, DeprecatedPaintLayer* endLayer)
 {
     if (startLayer == endLayer)