Hide non-composited native scrollbars.

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

 /*
  * Copyright (C) 2011 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 157 matching lines @@
     if (m_allowHitTest == DisallowHitTest)
         return NoPart;
 
     return ScrollbarTheme::hitTest(scrollbar, position);
 }
 
 ScrollbarThemeOverlay& ScrollbarThemeOverlay::mobileTheme()
 {
     static ScrollbarThemeOverlay* theme;
     if (!theme) {
-        WebThemeEngine::ScrollbarStyle style = { 3, 3, 0x80808080 }; // default style
-        if (Platform::current()->themeEngine()) {
-            Platform::current()->themeEngine()->getOverlayScrollbarStyle(&style);
+        if (RuntimeEnabledFeatures::hideScrollbarsEnabled()) {
+            theme = new ScrollbarThemeOverlay(0, 0, ScrollbarThemeOverlay::DisallowHitTest, Color());
+        } else {
+            WebThemeEngine::ScrollbarStyle style = { 3, 3, 0x80808080 }; // default style
+            if (Platform::current()->themeEngine()) {
+                Platform::current()->themeEngine()->getOverlayScrollbarStyle(&style);
+            }
+            theme = new ScrollbarThemeOverlay(style.thumbThickness, style.scrollbarMargin, ScrollbarThemeOverlay::DisallowHitTest, Color(style.color));
         }
-        theme = new ScrollbarThemeOverlay(style.thumbThickness, style.scrollbarMargin, ScrollbarThemeOverlay::DisallowHitTest, Color(style.color));
     }
     return *theme;
 }
 
 } // namespace blink