MainFrame scrollbars should work with RFV instead of FV

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

Index: third_party/WebKit/Source/core/frame/FrameView.h
diff --git a/third_party/WebKit/Source/core/frame/FrameView.h b/third_party/WebKit/Source/core/frame/FrameView.h
index c68752363135fa17879613f10c06f4ef641d5330..c416cd31f06e29aefa70df749cf8f7eb619bc7f2 100644
--- a/third_party/WebKit/Source/core/frame/FrameView.h
+++ b/third_party/WebKit/Source/core/frame/FrameView.h
@@ -465,6 +465,8 @@ class CORE_EXPORT FrameView final
   }
   LayoutScrollbarPart* scrollCorner() const override { return m_scrollCorner; }
 
+  void updateScrollbars() override;
+
   void positionScrollbarLayers();
 
   // Functions for setting and retrieving the scrolling mode in each axis
@@ -760,11 +762,7 @@ class CORE_EXPORT FrameView final
       bool& newHasVerticalScrollbar,
       const IntSize& docSize,
       ComputeScrollbarExistenceOption = FirstPass) const;
-  void updateScrollbarGeometry();
 
-  // Called to update the scrollbars to accurately reflect the state of the
-  // view.
-  void updateScrollbars();
   void updateScrollbarsIfNeeded();
 
   class InUpdateScrollbarsScope {
@@ -797,6 +795,11 @@ class CORE_EXPORT FrameView final
     // setHas*Scrollbar functions above.
     Scrollbar* createScrollbar(ScrollbarOrientation) override;
 
+    // Updates the scrollbar geometry given the size of the frame view rect.
+    void updateScrollbarGeometry(IntSize viewSize);
+
+    ScrollableArea* scrollableArea() const;
+
    protected:
     void destroyScrollbar(ScrollbarOrientation) override;
   };
@@ -876,10 +879,6 @@ class CORE_EXPORT FrameView final
   static bool computeCompositedSelection(LocalFrame&, CompositedSelection&);
   void updateCompositedSelectionIfNeeded();
 
-  // Returns true if the FrameView's own scrollbars overlay its content when
-  // visible.
-  bool hasOverlayScrollbars() const;
-
   // Returns true if the frame should use custom scrollbars. If true, one of
   // either |customScrollbarElement| or |customScrollbarFrame| will be set to
   // the element or frame which owns the scrollbar with the other set to null.