cc: Make occlusion a draw property.

cc/layers/layer_impl.h

Index: cc/layers/layer_impl.h
diff --git a/cc/layers/layer_impl.h b/cc/layers/layer_impl.h
index 62d428e8dd99b853eb424b982737615caaa74657..24ab4ed4291bbb5778b515aa06994f84d2d712e3 100644
--- a/cc/layers/layer_impl.h
+++ b/cc/layers/layer_impl.h
@@ -219,11 +219,6 @@ class CC_EXPORT LayerImpl : public LayerAnimationValueObserver,
   virtual RenderPassId FirstContributingRenderPassId() const;
   virtual RenderPassId NextContributingRenderPassId(RenderPassId id) const;
 
-  // Updates the layer's tiles. This should return true if meaningful work was
-  // done. That is, if an early-out was hit and as a result the internal state
-  // of tiles didn't change, this function should return false.
-  virtual bool UpdateTiles(const Occlusion& occlusion_in_layer_space,
-                           bool resourceless_software_draw);
   virtual void NotifyTileStateChanged(const Tile* tile) {}
 
   virtual ScrollbarLayerImplBase* ToScrollbarLayer();