Make DisplayItemClient an interface

third_party/WebKit/Source/platform/scroll/ScrollbarTheme.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 152 matching lines @@
     } else if (backButtonRect(scrollbar, BackButtonEndPart).contains(testPosition)) {
         result = BackButtonEndPart;
     } else if (forwardButtonRect(scrollbar, ForwardButtonStartPart).contains(testPosition)) {
         result = ForwardButtonStartPart;
     } else if (forwardButtonRect(scrollbar, ForwardButtonEndPart).contains(testPosition)) {
         result = ForwardButtonEndPart;
     }
     return result;
 }
 
-void ScrollbarTheme::paintScrollCorner(GraphicsContext* context, const DisplayItemClientWrapper& displayItemClient, const IntRect& cornerRect)
+void ScrollbarTheme::paintScrollCorner(GraphicsContext* context, const DisplayItemClient& displayItemClient, const IntRect& cornerRect)
 {
     if (cornerRect.isEmpty())
         return;
 
     if (DrawingRecorder::useCachedDrawingIfPossible(*context, displayItemClient, DisplayItem::ScrollbarCorner))
         return;
 
     DrawingRecorder recorder(*context, displayItemClient, DisplayItem::ScrollbarCorner, cornerRect);
 #if OS(MACOSX)
     context->fillRect(cornerRect, Color::white);
@@ skipping 148 matching lines @@
         return DisplayItem::ScrollbarBackTrack;
     case ForwardTrackPart:
         return DisplayItem::ScrollbarForwardTrack;
     default:
         ASSERT_NOT_REACHED();
         return DisplayItem::ScrollbarBackTrack;
     }
 }
 
 } // namespace blink