Make DisplayItemClient an interface

third_party/WebKit/Source/core/paint/LayoutObjectDrawingRecorder.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 LayoutObjectDrawingRecorder_h
 #define LayoutObjectDrawingRecorder_h
 
 #include "core/layout/LayoutObject.h"
 #include "core/paint/PaintPhase.h"
 #include "platform/geometry/LayoutPoint.h"
@@ skipping 52 matching lines @@
 
 private:
     static void updatePaintOffsetIfNeeded(PaintController& paintController, const LayoutObject& layoutObject, const LayoutPoint& paintOffset)
     {
         if (!RuntimeEnabledFeatures::slimmingPaintOffsetCachingEnabled() || paintController.skippingCache())
             return;
 
         if (layoutObject.paintOffsetChanged(paintOffset))
             paintController.invalidatePaintOffset(layoutObject);
         else
-            ASSERT(!paintController.paintOffsetWasInvalidated(layoutObject.displayItemClient()) || !paintController.clientCacheIsValid(layoutObject.displayItemClient()));
+            ASSERT(!paintController.paintOffsetWasInvalidated(layoutObject) || !paintController.clientCacheIsValid(layoutObject));
 
         layoutObject.mutableForPainting().setPreviousPaintOffset(paintOffset);
     }
 
     Optional<DisplayItemCacheSkipper> m_cacheSkipper;
     Optional<DrawingRecorder> m_drawingRecorder;
 };
 
 } // namespace blink
 
 #endif // LayoutObjectDrawingRecorder_h