cc: Refactor how picture layers are exposed to the tile manager.

cc/trees/layer_tree_impl.cc

Index: cc/trees/layer_tree_impl.cc
diff --git a/cc/trees/layer_tree_impl.cc b/cc/trees/layer_tree_impl.cc
index 9932a33be03d59d47c6ea65ad437c8a46b4e76a6..6a35981f74f0861ebcc0cf5af5d5ed3a00c5c25c 100644
--- a/cc/trees/layer_tree_impl.cc
+++ b/cc/trees/layer_tree_impl.cc
@@ -1275,4 +1275,12 @@ LayerImpl* LayerTreeImpl::FindLayerThatIsHitByPointInTouchHandlerRegion(
   return data_for_recursion.closest_match;
 }
 
+void LayerTreeImpl::RegisterPictureLayerImpl(PictureLayerImpl* layer) {
+  layer_tree_host_impl_->RegisterPictureLayerImpl(layer);
+}
+
+void LayerTreeImpl::UnregisterPictureLayerImpl(PictureLayerImpl* layer) {
+  layer_tree_host_impl_->UnregisterPictureLayerImpl(layer);
+}
+
 }  // namespace cc