Revert of Make GraphicsLayer the DisplayItemClient for scrollbars composited via PaintLayerCompositor.

third_party/WebKit/Source/platform/graphics/paint/DisplayItem.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 DisplayItem_h
 #define DisplayItem_h
 
 #include "platform/PlatformExport.h"
 #include "platform/graphics/ContiguousContainer.h"
 #include "platform/graphics/paint/DisplayItemClient.h"
@@ skipping 74 matching lines @@
         ScrollbarBackButtonStart,
         ScrollbarBackground,
         ScrollbarBackTrack,
         ScrollbarCorner,
         ScrollbarForwardButtonEnd,
         ScrollbarForwardButtonStart,
         ScrollbarForwardTrack,
         ScrollbarThumb,
         ScrollbarTickmarks,
         ScrollbarTrackBackground,
-        ScrollbarCompositedScrollbar,
         SelectionTint,
         TableCellBackgroundFromColumnGroup,
         TableCellBackgroundFromColumn,
         TableCellBackgroundFromSection,
         TableCellBackgroundFromRow,
         // Table collapsed borders can be painted together (e.g., left & top) but there are at most 4 phases of collapsed
         // border painting for a single cell. To disambiguate these phases of collapsed border painting, a mask is used.
         // TableCollapsedBorderBase can be larger than TableCollapsedBorderUnalignedBase to ensure the base lower bits are 0's.
         TableCollapsedBorderUnalignedBase,
         TableCollapsedBorderBase = (((TableCollapsedBorderUnalignedBase - 1) >> 4) + 1) << 4,
@@ skipping 292 matching lines @@
     bool isEndAndPairedWith(DisplayItem::Type otherType) const override = 0;
 #endif
 
 private:
     bool isEnd() const final { return true; }
 };
 
 } // namespace blink
 
 #endif // DisplayItem_h