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

third_party/WebKit/Source/platform/graphics/paint/DisplayItemList.h

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef DisplayItemList_h
 #define DisplayItemList_h
 
 #include "platform/graphics/ContiguousContainer.h"
 #include "platform/graphics/paint/DisplayItem.h"
 #include "platform/graphics/paint/Transform3DDisplayItem.h"
@@ skipping 54 matching lines @@
    private:
     Iterator m_begin;
     Iterator m_end;
   };
   Range<iterator> itemsInPaintChunk(const PaintChunk&);
   Range<const_iterator> itemsInPaintChunk(const PaintChunk&) const;
 
   enum JsonOptions {
     Default = 0,
     ShowPictures = 1,
-    SkipNonDrawings = 2,
-    ShowClientDebugName = 4,
+    SkipNonDrawings = 1 << 1,
+    ShowClientDebugName = 1 << 2,
+    ShownOnlyDisplayItemTypes = 1 << 3
   };
   typedef unsigned JsonFlags;
 
   std::unique_ptr<JSONArray> subsequenceAsJSON(size_t beginIndex,
                                                size_t endIndex,
                                                JsonFlags options) const;
 
  private:
   Vector<IntRect> m_visualRects;
 };
 
 }  // namespace blink
 
 #endif  // DisplayItemList_h