Transfer LayerImpl ownership to LayerTreeImpl

cc/test/fake_layer_tree_host_impl.cc

Index: cc/test/fake_layer_tree_host_impl.cc
diff --git a/cc/test/fake_layer_tree_host_impl.cc b/cc/test/fake_layer_tree_host_impl.cc
index 17963c3692300f2ccaa003690112547a26e40c98..5d3b510eababda19910029bcdf8e1aedbb84d3d7 100644
--- a/cc/test/fake_layer_tree_host_impl.cc
+++ b/cc/test/fake_layer_tree_host_impl.cc
@@ -86,7 +86,7 @@ int FakeLayerTreeHostImpl::RecursiveUpdateNumChildren(LayerImpl* layer) {
   int num_children_that_draw_content = 0;
   for (size_t i = 0; i < layer->children().size(); ++i) {
     num_children_that_draw_content +=
-        RecursiveUpdateNumChildren(layer->children()[i].get());
+        RecursiveUpdateNumChildren(layer->children()[i]);
   }
   layer->SetNumDescendantsThatDrawContent(num_children_that_draw_content);
   return num_children_that_draw_content + (layer->DrawsContent() ? 1 : 0);