Insert pinch zoom virtual viewport layers to graphics layer tree.

Source/core/platform/graphics/GraphicsLayer.cpp

 /*
  * Copyright (C) 2009 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 702 matching lines @@
     return static_cast<double>(4 * size().width()) * size().height();
 }
 
 void GraphicsLayer::resetTrackedRepaints()
 {
     repaintRectMap().remove(this);
 }
 
 void GraphicsLayer::addRepaintRect(const FloatRect& repaintRect)
 {
-    if (m_client->isTrackingRepaints()) {
+    if (m_client && m_client->isTrackingRepaints()) {

[jamesr, 2013/06/14 20:55:46]

I think it'd be better to always create a GraphicsLayerClient, even if it's a
no-op.  The GraphicsLayerClient interface is small

[wjmaclean, 2013/06/17 17:45:27]

OK, done.

That being said, it seems weirdly inconsistent that we check in numerous other
places to see if we have a valid client, but not here. I would think either we
should always check, or never check. (It was primarily the existence of these
other checks that convinced me to code it with a null client ... a previous
version of this CL had a client ;-) )

         FloatRect largestRepaintRect(FloatPoint(), m_size);
         largestRepaintRect.intersect(repaintRect);
         RepaintMap::iterator repaintIt = repaintRectMap().find(this);
         if (repaintIt == repaintRectMap().end()) {
             Vector<FloatRect> repaintRects;
             repaintRects.append(largestRepaintRect);
             repaintRectMap().set(this, repaintRects);
         } else {
             Vector<FloatRect>& repaintRects = repaintIt->value;
             repaintRects.append(largestRepaintRect);
@@ skipping 195 matching lines @@
 }
 
 void GraphicsLayer::reportMemoryUsage(MemoryObjectInfo* memoryObjectInfo) const
 {
     MemoryClassInfo info(memoryObjectInfo, this, PlatformMemoryTypes::Layers);
     info.addMember(m_children, "children");
     info.addMember(m_parent, "parent");
     info.addMember(m_maskLayer, "maskLayer");
     info.addMember(m_replicaLayer, "replicaLayer");
     info.addMember(m_replicatedLayer, "replicatedLayer");
-    info.ignoreMember(m_client);
+    if (m_client)
+        info.ignoreMember(m_client);
     info.addMember(m_name, "name");
     info.addMember(m_nameBase, "nameBase");
     info.addMember(m_layer, "layer");
     info.addMember(m_imageLayer, "imageLayer");
     info.addMember(m_contentsLayer, "contentsLayer");
     info.addMember(m_linkHighlight, "linkHighlight");
     info.addMember(m_opaqueRectTrackingContentLayerDelegate, "opaqueRectTrackingContentLayerDelegate");
     info.addMember(m_animationIdMap, "animationIdMap");
     info.addMember(m_scrollableArea, "scrollableArea");
 }
@@ skipping 415 matching lines @@
 #ifndef NDEBUG
 void showGraphicsLayerTree(const WebCore::GraphicsLayer* layer)
 {
     if (!layer)
         return;
 
     String output = layer->layerTreeAsText(LayerTreeAsTextDebug | LayerTreeAsTextIncludeVisibleRects);
     fprintf(stderr, "%s\n", output.utf8().data());
 }
 #endif