Enabled using viewport on desktop browsers behind experimental flag

Source/core/page/FrameView.h

 /*
    Copyright (C) 1997 Martin Jones (mjones@kde.org)
              (C) 1998 Waldo Bastian (bastian@kde.org)
              (C) 1998, 1999 Torben Weis (weis@kde.org)
              (C) 1999 Lars Knoll (knoll@kde.org)
              (C) 1999 Antti Koivisto (koivisto@kde.org)
    Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
@@ skipping 68 matching lines @@
     RenderView* renderView() const { return m_frame ? m_frame->contentRenderer() : 0; }
 
     int mapFromLayoutToCSSUnits(LayoutUnit);
     LayoutUnit mapFromCSSToLayoutUnits(int);
 
     LayoutUnit marginWidth() const { return m_margins.width(); } // -1 means default
     LayoutUnit marginHeight() const { return m_margins.height(); } // -1 means default
     void setMarginWidth(LayoutUnit);
     void setMarginHeight(LayoutUnit);
 
+    virtual IntSize layoutSize(VisibleContentRectIncludesScrollbars = ExcludeScrollbars) const;
+    void setLayoutSize(const IntSize&);
+
     virtual void setCanHaveScrollbars(bool);
     void updateCanHaveScrollbars();
 
     virtual PassRefPtr<Scrollbar> createScrollbar(ScrollbarOrientation);
 
     virtual void setContentsSize(const IntSize&);
 
     void layout(bool allowSubtree = true);
     bool didFirstLayout() const;
     void layoutTimerFired(Timer<FrameView>*);
@@ skipping 358 matching lines @@
     unsigned m_nestedLayoutCount;
     Timer<FrameView> m_postLayoutTasksTimer;
     bool m_firstLayoutCallbackPending;
 
     bool m_firstLayout;
     bool m_isTransparent;
     Color m_baseBackgroundColor;
     IntSize m_lastViewportSize;
     float m_lastZoomFactor;
 
+    // Client can explicitly set a layout size, if unset the frameRect is used
+    IntSize m_layoutSize;
+
     AtomicString m_mediaType;
     AtomicString m_mediaTypeWhenNotPrinting;
 
     OwnPtr<FrameActionScheduler> m_actionScheduler;
 
     bool m_overflowStatusDirty;
     bool m_horizontalOverflow;
     bool m_verticalOverflow;
     RenderObject* m_viewportRenderer;
 
@@ skipping 102 matching lines @@
     ASSERT(!widget || widget->isFrameView());
     return static_cast<const FrameView*>(widget);
 }
 
 // This will catch anyone doing an unnecessary cast.
 void toFrameView(const FrameView*);
 
 } // namespace WebCore
 
 #endif // FrameView_h