TaskGraphRunner refactor

cc/test/layer_tree_test.cc

Index: cc/test/layer_tree_test.cc
diff --git a/cc/test/layer_tree_test.cc b/cc/test/layer_tree_test.cc
index 0578128532d1db41387f2f40ddb888f7e75674dd..655c5d4eafb71d09a43d713e7bff8af53ad34429 100644
--- a/cc/test/layer_tree_test.cc
+++ b/cc/test/layer_tree_test.cc
@@ -1150,6 +1150,10 @@ void LayerTreeTest::DestroyLayerTreeHost() {
   layer_tree_host_ = nullptr;
 }
 
+TaskGraphRunner* LayerTreeTest::task_graph_runner() const {
+  return task_graph_runner_.get();
+}
+
 LayerTreeHost* LayerTreeTest::layer_tree_host() {
   // We check for a null task_runner_provider here as we sometimes ask for the
   // layer tree host when the task_runner_provider does not exist, often for