Improve code readibility of PaintPropertyTreeBuilder

third_party/WebKit/Source/core/layout/api/LayoutItem.h

 // Copyright 2016 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 LayoutItem_h
 #define LayoutItem_h
 
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/layout/LayoutObject.h"
 
@@ skipping 276 matching lines @@
     bool mapToVisualRectInAncestorSpace(const LayoutBoxModelObject* ancestor, LayoutRect& layoutRect, VisualRectFlags flags = DefaultVisualRectFlags) const
     {
         return m_layoutObject->mapToVisualRectInAncestorSpace(ancestor, layoutRect, flags);
     }
 
     Color resolveColor(int colorProperty) const
     {
         return m_layoutObject->resolveColor(colorProperty);
     }
 
-    ObjectPaintProperties* objectPaintProperties() const
+    const ObjectPaintProperties* objectPaintProperties() const
     {
         return m_layoutObject->objectPaintProperties();
     }
 
 protected:
     LayoutObject* layoutObject() { return m_layoutObject; }
     const LayoutObject* layoutObject() const { return m_layoutObject; }
 
 private:
     LayoutObject* m_layoutObject;
 
     friend class LayoutAPIShim;
 };
 
 } // namespace blink
 
 #endif // LayoutItem_h