Add optional debugging output of what paint chunks go into what layers.

third_party/WebKit/Source/core/frame/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
@@ skipping 340 matching lines @@
   // FIXME: Remove this method once plugin loading is decoupled from layout.
   void flushAnyPendingPostLayoutTasks();
 
   bool shouldSuspendScrollAnimations() const override;
   void scrollbarStyleChanged() override;
 
   LayoutReplaced* embeddedReplacedContent() const;
 
   static void setInitialTracksPaintInvalidationsForTesting(bool);
 
+  void setIsStoringCompositedLayerDebugInfo(bool val) {
+    m_isStoringCompositedLayerDebugInfo = val;
+  }
+
   // These methods are for testing.
   void setTracksPaintInvalidations(bool);
   bool isTrackingPaintInvalidations() const {
     return m_trackedObjectPaintInvalidations.get();
   }
   void trackObjectPaintInvalidation(const DisplayItemClient&,
                                     PaintInvalidationReason);
   std::unique_ptr<JSONArray> trackedObjectPaintInvalidationsAsJSON() const;
 
   using ScrollableAreaSet = HeapHashSet<Member<ScrollableArea>>;
@@ skipping 754 matching lines @@
   struct ObjectPaintInvalidation {
     String name;
     PaintInvalidationReason reason;
   };
   std::unique_ptr<Vector<ObjectPaintInvalidation>>
       m_trackedObjectPaintInvalidations;
 
   // For Slimming Paint v2 only.
   std::unique_ptr<PaintController> m_paintController;
   std::unique_ptr<PaintArtifactCompositor> m_paintArtifactCompositor;
+  bool m_isStoringCompositedLayerDebugInfo;
 };
 
 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 didMeaningfulLayout.  The first few hundred characters rarely
   // contain the interesting content of the page.
   static const unsigned visualCharacterThreshold = 200;
@@ skipping 20 matching lines @@
                   widget.isFrameView());
 DEFINE_TYPE_CASTS(FrameView,
                   ScrollableArea,
                   scrollableArea,
                   scrollableArea->isFrameView(),
                   scrollableArea.isFrameView());
 
 }  // namespace blink
 
 #endif  // FrameView_h