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

cc/layer.h

Index: cc/layer.h
diff --git a/cc/layer.h b/cc/layer.h
index f95482b7ef5a05b683d8b9ec976efaf4af1c843d..25551b3ef1f34e0f01e0e3f7effa8a5640fabc5f 100644
--- a/cc/layer.h
+++ b/cc/layer.h
@@ -199,6 +199,9 @@ public:
 
     void setIsDrawable(bool);
 
+    void setVisible(bool);

[piman, 2013/01/30 21:38:50]

Nit: we may want to name that as "setSubtreeVisible" or something that carries
the fact that this applies to this layer and its entire subtree, not just this
layer.

+    bool visible() const { return m_visible; }
+
     void setReplicaLayer(Layer*);
     Layer* replicaLayer() { return m_replicaLayer.get(); }
     const Layer* replicaLayer() const { return m_replicaLayer.get(); }
@@ -379,6 +382,7 @@ private:
     bool m_isContainerForFixedPositionLayers;
     bool m_fixedToContainerLayer;
     bool m_isDrawable;
+    bool m_visible;
     bool m_masksToBounds;
     bool m_contentsOpaque;
     bool m_doubleSided;