MainFrame scrollbars should work with RFV instead of FV

third_party/WebKit/Source/platform/scroll/ScrollableArea.cpp

 /*
  * Copyright (c) 2010, Google Inc. All rights reserved.
  * Copyright (C) 2008, 2011 Apple Inc. All Rights Reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
@@ skipping 371 matching lines @@
   }
 }
 
 void ScrollableArea::contentsResized() {
   showOverlayScrollbars();
   if (ScrollAnimatorBase* scrollAnimator = existingScrollAnimator())
     scrollAnimator->contentsResized();
 }
 
 bool ScrollableArea::hasOverlayScrollbars() const {
-  Scrollbar* vScrollbar = verticalScrollbar();
-  if (vScrollbar && vScrollbar->isOverlayScrollbar())
-    return true;
-  Scrollbar* hScrollbar = horizontalScrollbar();
-  return hScrollbar && hScrollbar->isOverlayScrollbar();
+  return (horizontalScrollbar() &&
+          horizontalScrollbar()->isOverlayScrollbar()) ||
+         (verticalScrollbar() && verticalScrollbar()->isOverlayScrollbar());
 }
 
 void ScrollableArea::setScrollbarOverlayColorTheme(
     ScrollbarOverlayColorTheme overlayTheme) {
   m_scrollbarOverlayColorTheme = overlayTheme;
 
   if (Scrollbar* scrollbar = horizontalScrollbar()) {
     ScrollbarTheme::theme().updateScrollbarOverlayColorTheme(*scrollbar);
     scrollbar->setNeedsPaintInvalidation(AllParts);
   }
@@ skipping 247 matching lines @@
   return IntSize(std::max(0, size.width() - verticalScrollbarWidth()),
                  std::max(0, size.height() - horizontalScrollbarHeight()));
 }
 
 DEFINE_TRACE(ScrollableArea) {
   visitor->trace(m_scrollAnimator);
   visitor->trace(m_programmaticScrollAnimator);
 }
 
 }  // namespace blink