Plumbs through support for painting the scrollbarcorner

ui/native_theme/native_theme_aurawin.h

Index: ui/native_theme/native_theme_aurawin.h
diff --git a/ui/native_theme/native_theme_aurawin.h b/ui/native_theme/native_theme_aurawin.h
index c1dadd0c65f916194661767d38590862a551b4eb..163d1ed814b1fecc91c8d793e8d1b9a01bba37f9 100644
--- a/ui/native_theme/native_theme_aurawin.h
+++ b/ui/native_theme/native_theme_aurawin.h
@@ -42,6 +42,9 @@ class NATIVE_THEME_EXPORT NativeThemeAuraWin : public NativeThemeAura {
                                    Part part,
                                    State state,
                                    const gfx::Rect& rect) const OVERRIDE;
+  virtual void PaintScrollbarCorner(SkCanvas* canvas,
+                                    State state,
+                                    const gfx::Rect& rect) const OVERRIDE;
 
   // Returns the NineImagePainter used to paint the specified state, creating if
   // necessary. If no image is provided for the specified state the normal state