CompositingReasonFinder should use a virtual function instead of a nest of branches

Source/core/rendering/RenderObject.h

 /*
  * Copyright (C) 2000 Lars Knoll (knoll@kde.org)
  *           (C) 2000 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2009 Google 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 17 matching lines @@
 
 #include "core/dom/Element.h"
 #include "core/dom/Position.h"
 #include "core/dom/StyleEngine.h"
 #include "core/fetch/ImageResourceClient.h"
 #include "core/rendering/compositing/CompositingState.h"
 #include "core/rendering/PaintPhase.h"
 #include "core/rendering/RenderObjectChildList.h"
 #include "core/rendering/ScrollAlignment.h"
 #include "core/rendering/SubtreeLayoutScope.h"
+#include "core/rendering/compositing/CompositingTriggers.h"
 #include "core/rendering/style/RenderStyle.h"
 #include "core/rendering/style/StyleInheritedData.h"
 #include "platform/geometry/FloatQuad.h"
 #include "platform/geometry/LayoutRect.h"
+#include "platform/graphics/CompositingReasons.h"
 #include "platform/transforms/TransformationMatrix.h"
 
 namespace WebCore {
 
 class AffineTransform;
 class Cursor;
 class Document;
 class HitTestLocation;
 class HitTestResult;
 class InlineBox;
@@ skipping 617 matching lines @@
     void forceChildLayout();
 
     // used for element state updates that cannot be fixed with a
     // repaint and do not need a relayout
     virtual void updateFromElement() { }
 
     virtual void addAnnotatedRegions(Vector<AnnotatedRegionValue>&);
     void collectAnnotatedRegions(Vector<AnnotatedRegionValue>&);
 
     CompositingState compositingState() const;
+    virtual CompositingReasons additionalCompositingReasons(CompositingTriggerFlags) const;
+
     bool acceleratedCompositingForOverflowScrollEnabled() const;
     // FIXME: This is a temporary flag and should be removed once accelerated
     // overflow scroll is ready (crbug.com/254111).
     bool compositorDrivenAcceleratedScrollingEnabled() const;
 
     bool hitTest(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestFilter = HitTestAll);
     virtual void updateHitTestResult(HitTestResult&, const LayoutPoint&);
     virtual bool nodeAtPoint(const HitTestRequest&, HitTestResult&, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction);
 
     virtual PositionWithAffinity positionForPoint(const LayoutPoint&);
@@ skipping 728 matching lines @@
 void showTree(const WebCore::RenderObject*);
 void showLineTree(const WebCore::RenderObject*);
 void showRenderTree(const WebCore::RenderObject* object1);
 // We don't make object2 an optional parameter so that showRenderTree
 // can be called from gdb easily.
 void showRenderTree(const WebCore::RenderObject* object1, const WebCore::RenderObject* object2);
 
 #endif
 
 #endif // RenderObject_h