Handle ui::Layer's visibility using cc::Layer's m_isDrawable flag

ui/compositor/layer.h

Index: ui/compositor/layer.h
diff --git a/ui/compositor/layer.h b/ui/compositor/layer.h
index b35cf0bdff2df6211a762a2325f6b980c16252a0..3bd460c2210a7380973c2315a2af61a12a18f232 100644
--- a/ui/compositor/layer.h
+++ b/ui/compositor/layer.h
@@ -341,6 +341,8 @@ class COMPOSITOR_EXPORT Layer
   // Set all filters which got applied to the layer background.
   void SetLayerBackgroundFilters();
 
+  void UpdateIsDrawn();
+
   const LayerType type_;
 
   Compositor* compositor_;
@@ -359,6 +361,9 @@ class COMPOSITOR_EXPORT Layer
   // Visibility of this layer. See SetVisible/IsDrawn for more details.
   bool visible_;
 
+  // Computed based on the visibility of this layer and its ancestors.
+  bool is_drawn_;
+
   bool force_render_surface_;
 
   bool fills_bounds_opaquely_;