Fix overflow:overlay scrollbar width for paint.

third_party/WebKit/Source/core/frame/RootFrameViewport.h

Index: third_party/WebKit/Source/core/frame/RootFrameViewport.h
diff --git a/third_party/WebKit/Source/core/frame/RootFrameViewport.h b/third_party/WebKit/Source/core/frame/RootFrameViewport.h
index 33ccd9803a3fd605c01c344f1136ab47fe44d31e..72c87ed639f7c4c2d864304f34e3728d05ff1892 100644
--- a/third_party/WebKit/Source/core/frame/RootFrameViewport.h
+++ b/third_party/WebKit/Source/core/frame/RootFrameViewport.h
@@ -86,9 +86,11 @@ class CORE_EXPORT RootFrameViewport final
   GraphicsLayer* layerForVerticalScrollbar() const override;
   GraphicsLayer* layerForScrollCorner() const override;
   int horizontalScrollbarHeight(
-      OverlayScrollbarClipBehavior = IgnoreOverlayScrollbarSize) const override;
+      OverlayScrollbarClipBehavior =
+          IgnorePlatformOverlayScrollbarSize) const override;
   int verticalScrollbarWidth(
-      OverlayScrollbarClipBehavior = IgnoreOverlayScrollbarSize) const override;
+      OverlayScrollbarClipBehavior =
+          IgnorePlatformOverlayScrollbarSize) const override;
   ScrollResult userScroll(ScrollGranularity, const FloatSize&) override;
   bool scrollAnimatorEnabled() const override;
   HostWindow* getHostWindow() const override;