Do-not-commit: Count layout tree memory usage

third_party/WebKit/Source/core/paint/PaintLayer.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 204 matching lines @@
   WTF_MAKE_NONCOPYABLE(PaintLayer);
 
  public:
   PaintLayer(LayoutBoxModelObject&);
   ~PaintLayer() override;
 
   // DisplayItemClient methods
   String debugName() const final;
   LayoutRect visualRect() const final;
 
+  char approximateHeapMemoryUsage() const;
+
   LayoutBoxModelObject& layoutObject() const { return m_layoutObject; }
   LayoutBox* layoutBox() const {
     return m_layoutObject.isBox() ? &toLayoutBox(m_layoutObject) : 0;
   }
   PaintLayer* parent() const { return m_parent; }
   PaintLayer* previousSibling() const { return m_previous; }
   PaintLayer* nextSibling() const { return m_next; }
   PaintLayer* firstChild() const { return m_first; }
   PaintLayer* lastChild() const { return m_last; }
 
@@ skipping 1013 matching lines @@
 
 }  // namespace blink
 
 #ifndef NDEBUG
 // Outside the WebCore namespace for ease of invocation from gdb.
 CORE_EXPORT void showLayerTree(const blink::PaintLayer*);
 CORE_EXPORT void showLayerTree(const blink::LayoutObject*);
 #endif
 
 #endif  // Layer_h