Implement a method to access the non-composited content root layer picture pile.

cc/layer.h

Index: cc/layer.h
diff --git a/cc/layer.h b/cc/layer.h
index e7df4c08417438213d18838adcc177e5d440b765..b8903c8babfc7ee7f9c18378845c9ccd1a96fed6 100644
--- a/cc/layer.h
+++ b/cc/layer.h
@@ -200,6 +200,7 @@ public:
     bool hasContributingDelegatedRenderPasses() const { return false; }
 
     void setIsDrawable(bool);
+    bool isDrawable() const { return m_isDrawable; }
 
     void setReplicaLayer(Layer*);
     Layer* replicaLayer() { return m_replicaLayer.get(); }
@@ -284,6 +285,8 @@ public:
 
     gfx::Rect layerRectToContentRect(const gfx::RectF& layerRect) const;
 
+    virtual bool isPictureLayer() const;
+
     // In impl-side painting, this returns true if this layer type is not
     // compatible with the main thread running freely, such as a double-buffered
     // canvas that doesn't want to be triple-buffered across all three trees.