[Slimming Paint] Blink-side contiguous allocation of display items.

Source/core/layout/compositing/CompositedDeprecatedPaintLayerMapping.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 2110 matching lines @@
     } else {
         DeprecatedPaintLayerPaintingInfo paintingInfo(paintInfo.paintLayer, LayoutRect(dirtyRect), PaintBehaviorNormal, paintInfo.paintLayer->subpixelAccumulation());
 
         // DeprecatedPaintLayer::paintLayer assumes that the caller clips to the passed rect. Squashed layers need to do this clipping in software,
         // since there is no graphics layer to clip them precisely. Furthermore, in some cases we squash layers that need clipping in software
         // from clipping ancestors (see CompositedDeprecatedPaintLayerMapping::localClipRectForSquashedLayer()).
         // FIXME: Is it correct to clip to dirtyRect in slimming paint mode?
         // FIXME: Combine similar code here and LayerClipRecorder.
         dirtyRect.intersect(paintInfo.localClipRectForSquashedLayer);
         {
-            OwnPtr<DisplayItem> clipDisplayItem = ClipDisplayItem::create(*this, DisplayItem::ClipLayerOverflowControls, dirtyRect);
+            ClipDisplayItem clipDisplayItem(*this, DisplayItem::ClipLayerOverflowControls, dirtyRect);
             if (context->displayItemList()) {
                 ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());
                 if (!context->displayItemList()->displayItemConstructionIsDisabled())
-                    context->displayItemList()->add(clipDisplayItem.release());
+                    context->displayItemList()->add(clipDisplayItem);
             } else {
-                clipDisplayItem->replay(*context);
+                clipDisplayItem.replay(*context);
             }
         }
         DeprecatedPaintLayerPainter(*paintInfo.paintLayer).paintLayer(context, paintingInfo, paintLayerFlags);
         {
-            OwnPtr<DisplayItem> endClipDisplayItem = EndClipDisplayItem::create(*this, DisplayItem::clipTypeToEndClipType(DisplayItem::ClipLayerOverflowControls));
+            EndClipDisplayItem endClipDisplayItem(*this, DisplayItem::clipTypeToEndClipType(DisplayItem::ClipLayerOverflowControls));
             if (context->displayItemList()) {
                 ASSERT(RuntimeEnabledFeatures::slimmingPaintEnabled());
                 if (!context->displayItemList()->displayItemConstructionIsDisabled())
-                    context->displayItemList()->add(endClipDisplayItem.release());
+                    context->displayItemList()->add(endClipDisplayItem);
             } else {
-                endClipDisplayItem->replay(*context);
+                endClipDisplayItem.replay(*context);
             }
         }
     }
 }
 
 static void paintScrollbar(Scrollbar* scrollbar, GraphicsContext& context, const IntRect& clip)
 {
     if (!scrollbar)
         return;
 
@@ skipping 183 matching lines @@
     } else if (graphicsLayer == m_scrollingBlockSelectionLayer.get()) {
         name = "Scrolling Block Selection Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink