Made root translation layer the root when using pinch virtual viewport.

Source/core/rendering/compositing/RenderLayerCompositor.cpp

 /*
  * Copyright (C) 2009, 2010 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 894 matching lines @@
     CompositingReasons reasons = m_compositingReasonFinder.styleDeterminedReasons(layer->renderer());
     layer->setStyleDeterminedCompositingReasons(reasons);
 }
 
 void RenderLayerCompositor::updateDirectCompositingReasons(RenderLayer* layer)
 {
     CompositingReasons reasons = m_compositingReasonFinder.directReasons(layer, &m_needsToRecomputeCompositingRequirements);
     layer->setCompositingReasons(reasons, CompositingReasonComboAllDirectReasons);
 }
 
+void RenderLayerCompositor::setOverlayLayer(GraphicsLayer* layer)
+{
+    ASSERT(rootGraphicsLayer());
+
+    if (layer->parent() != m_overflowControlsHostLayer.get())
+        m_overflowControlsHostLayer->addChild(layer);
+}
+
 bool RenderLayerCompositor::canBeComposited(const RenderLayer* layer) const
 {
     // FIXME: We disable accelerated compositing for elements in a RenderFlowThread as it doesn't work properly.
     // See http://webkit.org/b/84900 to re-enable it.
     return m_hasAcceleratedCompositing && layer->isSelfPaintingLayer() && !layer->subtreeIsInvisible() && layer->renderer()->flowThreadState() == RenderObject::NotInsideFlowThread;
 }
 
 // Return true if the given layer has some ancestor in the RenderLayer hierarchy that clips,
 // up to the enclosing compositing ancestor. This is required because compositing layers are parented
 // according to the z-order hierarchy, yet clipping goes down the renderer hierarchy.
@@ skipping 493 matching lines @@
     } else if (graphicsLayer == m_scrollLayer.get()) {
         name = "LocalFrame Scrolling Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore