Add infrastructure for partial layouts

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 317 matching lines @@
     void setInProgrammaticScroll(bool programmaticScroll) { m_inProgrammaticScroll = programmaticScroll; }
 
     void setHasSoftwareFilters(bool hasSoftwareFilters) { m_hasSoftwareFilters = hasSoftwareFilters; }
     bool hasSoftwareFilters() const { return m_hasSoftwareFilters; }
 
     virtual bool isActive() const OVERRIDE;
 
     // DEPRECATED: Use viewportConstrainedVisibleContentRect() instead.
     IntSize scrollOffsetForFixedPosition() const;
 
+    bool shouldStopPartialLayout() const { return m_shouldStopPartialLayout; }
+    bool checkPartialLayoutComplete(RenderObject*);
+    void setStopLayoutAtRenderer(RenderObject* renderer) { m_stopLayoutAtRenderer = renderer; }
+    void resetPartialLayoutState() { m_stopLayoutAtRenderer = 0; m_shouldStopPartialLayout = false; }
+
 protected:
     virtual bool scrollContentsFastPath(const IntSize& scrollDelta, const IntRect& rectToScroll, const IntRect& clipRect);
     virtual void scrollContentsSlowPath(const IntRect& updateRect);
 
     virtual bool isVerticalDocument() const;
     virtual bool isFlippedDocument() const;
 
 private:
     explicit FrameView(Frame*);
 
@@ skipping 65 matching lines @@
 
     bool hasCustomScrollbars() const;
 
     virtual void updateScrollCorner();
 
     FrameView* parentFrameView() const;
 
     virtual AXObjectCache* axObjectCache() const;
     void removeFromAXObjectCache();
 
+#ifndef NDEBUG
+    void checkPartialLayoutAllowed();
+#endif
+
     static double s_currentFrameTimeStamp; // used for detecting decoded resource thrash in the cache
     static bool s_inPaintContents;
 
     LayoutSize m_size;
     LayoutSize m_margins;
 
     typedef HashSet<RenderObject*> RenderObjectSet;
     OwnPtr<RenderObjectSet> m_widgetUpdateSet;
     RefPtr<Frame> m_frame;
 
@@ skipping 88 matching lines @@
     OwnPtr<ViewportConstrainedObjectSet> m_viewportConstrainedObjects;
 
     static double s_normalDeferredRepaintDelay;
     static double s_initialDeferredRepaintDelayDuringLoading;
     static double s_maxDeferredRepaintDelayDuringLoading;
     static double s_deferredRepaintDelayIncrementDuringLoading;
 
     bool m_hasSoftwareFilters;
 
     float m_visibleContentScaleFactor;
+
+    bool m_shouldStopPartialLayout;
+    RenderObject* m_stopLayoutAtRenderer;
 };
 
+inline bool FrameView::checkPartialLayoutComplete(RenderObject* renderer)
+{
+    if (m_shouldStopPartialLayout)
+        return true;
+
+    if (renderer == m_stopLayoutAtRenderer) {
+#ifndef NDEBUG
+        checkPartialLayoutAllowed();
+#endif
+        m_shouldStopPartialLayout = true;

[eseidel, 2013/08/20 21:00:39]

I think when you do this, you should also clear m_stopLayoutAtRenderer.  We've
transitioned from the phase of "should we stop" to "we're stopping" and then
when we hit "stopped" we'll even clear the "we're stopping" bool.

[pdr., 2013/08/26 05:50:40]

Done.

+        return true;
+    }
+    return false;
+}
+
 inline void FrameView::incrementVisuallyNonEmptyCharacterCount(unsigned count)
 {
     if (m_isVisuallyNonEmpty)
         return;
     m_visuallyNonEmptyCharacterCount += count;
     // Use a threshold value to prevent very small amounts of visible content from triggering didFirstVisuallyNonEmptyLayout.
     // The first few hundred characters rarely contain the interesting content of the page.
     static const unsigned visualCharacterThreshold = 200;
     if (m_visuallyNonEmptyCharacterCount > visualCharacterThreshold)
         setIsVisuallyNonEmpty();
@@ skipping 31 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