Hide non-composited native scrollbars.

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

 /*
  * Copyright (c) 2008, 2009, Google 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.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 113 matching lines @@
     }
 
     return PartPaintingParams(paintPart, state);
 }
 
 } // namespace
 
 ScrollbarTheme& ScrollbarTheme::nativeTheme()
 {
     if (RuntimeEnabledFeatures::overlayScrollbarsEnabled()) {
+        if (RuntimeEnabledFeatures::hideScrollbarsEnabled()) {
+            DEFINE_STATIC_LOCAL(ScrollbarThemeOverlay, theme, (0, 0, ScrollbarThemeOverlay::DisallowHitTest, Color()));
+            return theme;
+        }
         DEFINE_STATIC_LOCAL(ScrollbarThemeOverlay, theme, (10, 0, ScrollbarThemeOverlay::AllowHitTest));
         return theme;
     }
 
     DEFINE_STATIC_LOCAL(ScrollbarThemeAura, theme, ());
     return theme;
 }
 
 int ScrollbarThemeAura::scrollbarThickness(ScrollbarControlSize controlSize)
 {
@@ skipping 197 matching lines @@
         int squareSize = scrollbar.width();
         return IntSize(squareSize, scrollbar.height() < 2 * squareSize ? scrollbar.height() / 2 : squareSize);
     }
 
     // HorizontalScrollbar
     int squareSize = scrollbar.height();
     return IntSize(scrollbar.width() < 2 * squareSize ? scrollbar.width() / 2 : squareSize, squareSize);
 }
 
 } // namespace blink