Make DisplayItem::replay const.

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

 // Copyright 2014 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 CachedDisplayItem_h
 #define CachedDisplayItem_h
 
 #include "platform/graphics/paint/DisplayItem.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 // A placeholder of a DrawingDisplayItem or a subtree in the new paint list of DisplayItemList,
 // to indicate that the DrawingDisplayItem/subtree has not been changed and should be replaced with
 // the cached DrawingDisplayItem/subtree when merging new paint list to cached paint list.
 class CachedDisplayItem final : public DisplayItem {
 public:
     CachedDisplayItem(const DisplayItemClientWrapper& client, Type type)
         : DisplayItem(client, type, sizeof(*this))
     {
         ASSERT(isCachedType(type));
     }
 
 private:
     // CachedDisplayItem is never replayed or appended to WebDisplayItemList.
-    void replay(GraphicsContext&) final { ASSERT_NOT_REACHED(); }
+    void replay(GraphicsContext&) const final { ASSERT_NOT_REACHED(); }
     void appendToWebDisplayItemList(WebDisplayItemList*) const final { ASSERT_NOT_REACHED(); }
 };
 
 } // namespace blink
 
 #endif // CachedDisplayItem_h