Makes visbility inherited. That is, in order for a window to be

ui/gfx/compositor/layer.h

 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_GFX_COMPOSITOR_LAYER_H_
 #define UI_GFX_COMPOSITOR_LAYER_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 84 matching lines @@
 
   // The bounds, relative to the parent.
   void SetBounds(const gfx::Rect& bounds);
   const gfx::Rect& bounds() const { return bounds_; }
 
   // The opacity of the layer. The opacity is applied to each pixel of the
   // texture (resulting alpha = opacity * alpha).
   float opacity() const { return opacity_; }
   void SetOpacity(float opacity);
 
-  // Sets |visible_|. The Layer is drawn by Draw() only when visible_ is true.
-  bool visible() const { return visible_; }
+  // Sets the visibility of the Layer. A Layer may be visible but not
+  // drawn. This happens if any ancestor of a Layer is not visible.
   void SetVisible(bool visible);
 
+  // Returns true if this Layer is drawn. A Layer is drawn only if all ancestors
+  // are visible.
+  bool IsDrawn() const;
+
   // Returns true if this layer can have a texture (has_texture_ is true)
   // and is not completely obscured by a child.
   bool ShouldDraw();
 
   // Converts a point from the coordinates of |source| to the coordinates of
   // |target|. Necessarily, |source| and |target| must inhabit the same Layer
   // tree.
   static void ConvertPointToLayer(const Layer* source,
                                   const Layer* target,
                                   gfx::Point* point);
@@ skipping 118 matching lines @@
   scoped_refptr<ui::Texture> texture_;
 
   Layer* parent_;
 
   std::vector<Layer*> children_;
 
   ui::Transform transform_;
 
   gfx::Rect bounds_;
 
+  // Visibility of this layer. See SetVisible/IsDrawn for more details.
   bool visible_;
 
   bool fills_bounds_opaquely_;
 
   gfx::Rect hole_rect_;
 
   gfx::Rect invalid_rect_;
 
   // If true the layer is always up to date.
   bool layer_updated_externally_;
 
   float opacity_;
 
   LayerDelegate* delegate_;
 
   scoped_ptr<LayerAnimator> animator_;
 
   DISALLOW_COPY_AND_ASSIGN(Layer);
 };
 
 }  // namespace ui
 
 #endif  // UI_GFX_COMPOSITOR_LAYER_H_