Implement lazy block layout prototype behind a runtime flag.

Source/core/rendering/RenderView.h

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2006 Apple Computer, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
@@ skipping 14 matching lines @@
 #include "core/page/FrameView.h"
 #include "core/platform/PODFreeListArena.h"
 #include "core/rendering/LayoutState.h"
 #include "core/rendering/RenderBlock.h"
 #include <wtf/OwnPtr.h>
 
 namespace WebCore {
 
 class FlowThreadController;
 class RenderLayerCompositor;
+class RenderLazyBlock;
 class RenderQuote;
 class RenderWidget;
 
 #if USE(3D_GRAPHICS)
 class CustomFilterGlobalContext;
 #endif
 
 class RenderView FINAL : public RenderBlock {
 public:
     explicit RenderView(Document*);
@@ skipping 151 matching lines @@
 
     void styleDidChange(StyleDifference, const RenderStyle* oldStyle);
 
     IntervalArena* intervalArena();
 
     IntSize viewportSize() const { return document()->viewportSize(); }
 
     void setRenderQuoteHead(RenderQuote* head) { m_renderQuoteHead = head; }
     RenderQuote* renderQuoteHead() const { return m_renderQuoteHead; }
 
+    void setFirstLazyBlock(RenderLazyBlock* block) { m_firstLazyBlock = block; }
+    RenderLazyBlock* firstLazyBlock() const { return m_firstLazyBlock; }
+    void markLazyBlocksForLayout();
+
     // FIXME: This is a work around because the current implementation of counters
     // requires walking the entire tree repeatedly and most pages don't actually use either
     // feature so we shouldn't take the performance hit when not needed. Long term we should
     // rewrite the counter and quotes code.
     void addRenderCounter() { m_renderCounterCount++; }
     void removeRenderCounter() { ASSERT(m_renderCounterCount > 0); m_renderCounterCount--; }
     bool hasRenderCounters() { return m_renderCounterCount; }
     
     virtual void addChild(RenderObject* newChild, RenderObject* beforeChild = 0) OVERRIDE;
 
@@ skipping 95 matching lines @@
     bool m_pageLogicalHeightChanged;
     LayoutState* m_layoutState;
     unsigned m_layoutStateDisableCount;
     OwnPtr<RenderLayerCompositor> m_compositor;
 #if USE(3D_GRAPHICS)
     OwnPtr<CustomFilterGlobalContext> m_customFilterGlobalContext;
 #endif
     OwnPtr<FlowThreadController> m_flowThreadController;
     RefPtr<IntervalArena> m_intervalArena;
 
+    RenderLazyBlock* m_firstLazyBlock;
     RenderQuote* m_renderQuoteHead;
     unsigned m_renderCounterCount;
 };
 
 inline RenderView* toRenderView(RenderObject* object)
 {
     ASSERT_WITH_SECURITY_IMPLICATION(!object || object->isRenderView());
     return static_cast<RenderView*>(object);
 }
 
@@ skipping 104 matching lines @@
     RenderObject::FlowThreadState m_flowThreadState;
     bool m_fragmenting;
 #ifndef NDEBUG
     LayoutState* m_layoutState;
 #endif
 };
 
 } // namespace WebCore
 
 #endif // RenderView_h