Feed ScrollableArea::showOverlayScrollbars into ScrollbarAnimationController.

third_party/WebKit/Source/core/layout/compositing/PaintLayerCompositor.h

 /*
  * Copyright (C) 2009 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:
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 207 matching lines @@
 
   Page* page() const;
 
   ScrollingCoordinator* scrollingCoordinator() const;
 
   void enableCompositingModeIfNeeded();
 
   bool requiresHorizontalScrollbarLayer() const;
   bool requiresVerticalScrollbarLayer() const;
   bool requiresScrollCornerLayer() const;
+  void showScrollbarLayersIfNeeded();
 
   void applyOverlayFullscreenVideoAdjustmentIfNeeded();
 
   void updateContainerSizes();
 
   // Checks the given graphics layer against the compositor's horizontal and
   // vertical scrollbar graphics layers, returning the associated Scrollbar
   // instance if any, else nullptr.
   Scrollbar* graphicsLayerToScrollbar(const GraphicsLayer*) const;
 
@@ skipping 44 matching lines @@
 
   // Layers for overflow controls
   std::unique_ptr<GraphicsLayer> m_layerForHorizontalScrollbar;
   std::unique_ptr<GraphicsLayer> m_layerForVerticalScrollbar;
   std::unique_ptr<GraphicsLayer> m_layerForScrollCorner;
 };
 
 }  // namespace blink
 
 #endif  // PaintLayerCompositor_h