Fix overflow:overlay scrollbar width for paint.

third_party/WebKit/Source/core/paint/PaintLayerClipper.h

 /*
  * Copyright (C) 2003, 2009, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2013 Intel Corporation. All rights reserved.
  *
  * Portions are Copyright (C) 1998 Netscape Communications Corporation.
  *
  * Other contributors:
  *   Robert O'Callahan <roc+@cs.cmu.edu>
  *   David Baron <dbaron@fas.harvard.edu>
  *   Christian Biesinger <cbiesinger@web.de>
@@ skipping 48 matching lines @@
 
 enum ShouldRespectOverflowClipType { IgnoreOverflowClip, RespectOverflowClip };
 
 class ClipRectsContext {
   STACK_ALLOCATED();
 
  public:
   ClipRectsContext(const PaintLayer* root,
                    ClipRectsCacheSlot slot,
                    OverlayScrollbarClipBehavior overlayScrollbarClipBehavior =
-                       IgnoreOverlayScrollbarSize,
+                       IgnorePlatformOverlayScrollbarSize,
                    const LayoutSize& accumulation = LayoutSize())
       : rootLayer(root),
         overlayScrollbarClipBehavior(overlayScrollbarClipBehavior),
         m_cacheSlot(slot),
         subPixelAccumulation(accumulation),
         respectOverflowClip(slot == PaintingClipRectsIgnoringOverflowClip
                                 ? IgnoreOverflowClip
                                 : RespectOverflowClip),
         respectOverflowClipForViewport(
             slot == RootRelativeClipRectsIgnoringViewportClip
@@ skipping 158 matching lines @@
 
   const PaintLayer& m_layer;
   GeometryMapper* m_geometryMapper;
 
   friend class PaintLayerClipperTest;
 };
 
 }  // namespace blink
 
 #endif  // LayerClipper_h