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

cc/layer_tree_host_common.cc

Index: cc/layer_tree_host_common.cc
diff --git a/cc/layer_tree_host_common.cc b/cc/layer_tree_host_common.cc
index bffc7db62a3c9001b034355b17915fb000ca1a60..9bc81b2525d74f6129e9e9ff01ae7c680963a080 100644
--- a/cc/layer_tree_host_common.cc
+++ b/cc/layer_tree_host_common.cc
@@ -221,7 +221,7 @@ static inline bool subtreeShouldBeSkipped(LayerImpl* layer)
     // The opacity of a layer always applies to its children (either implicitly
     // via a render surface or explicitly if the parent preserves 3D), so the
     // entire subtree can be skipped if this layer is fully transparent.
-    return !layer->opacity();
+    return !layer->opacity() || !layer->visible();
 }
 
 static inline bool subtreeShouldBeSkipped(Layer* layer)
@@ -229,7 +229,7 @@ static inline bool subtreeShouldBeSkipped(Layer* layer)
     // If the opacity is being animated then the opacity on the main thread is unreliable
     // (since the impl thread may be using a different opacity), so it should not be trusted.
     // In particular, it should not cause the subtree to be skipped.
-    return !layer->opacity() && !layer->opacityIsAnimating();
+    return (!layer->opacity() && !layer->opacityIsAnimating()) || !layer->visible();
 }
 
 // Called on each layer that could be drawn after all information from