Revert of Fix overflow:overlay scrollbar width for paint.

third_party/WebKit/Source/platform/scroll/ScrollTypes.h

Index: third_party/WebKit/Source/platform/scroll/ScrollTypes.h
diff --git a/third_party/WebKit/Source/platform/scroll/ScrollTypes.h b/third_party/WebKit/Source/platform/scroll/ScrollTypes.h
index b7e117f52d75a3fef92b7556d8eac4f0cb375d42..32d22c8071fd1e62bd29df498131f24396e2de42 100644
--- a/third_party/WebKit/Source/platform/scroll/ScrollTypes.h
+++ b/third_party/WebKit/Source/platform/scroll/ScrollTypes.h
@@ -43,12 +43,8 @@
   return ScrollOffset(p.x(), p.y());
 }
 
-// Platform overlay scrollbars are controlled and painted by the operating
-// system (e.g., OSX and Android).  CSS overlay scrollbars are created by
-// setting overflow:overlay, and they are painted by chromium.
 enum OverlayScrollbarClipBehavior {
-  IgnorePlatformOverlayScrollbarSize,
-  IgnorePlatformAndCSSOverlayScrollbarSize,
+  IgnoreOverlayScrollbarSize,
   ExcludeOverlayScrollbarSizeForHitTesting
 };