aura: Some change to how the client-lib is set up.

ui/aura/test/mus/test_window_tree_client_setup.cc

Index: ui/aura/test/mus/test_window_tree_client_setup.cc
diff --git a/ui/aura/test/mus/test_window_tree_client_setup.cc b/ui/aura/test/mus/test_window_tree_client_setup.cc
index e5f62ed3b97f3bc7bbc1f4bef59cd61adf26fd33..bc4ea5fe733c5022ff7b36bf56ff696f963cf3fe 100644
--- a/ui/aura/test/mus/test_window_tree_client_setup.cc
+++ b/ui/aura/test/mus/test_window_tree_client_setup.cc
@@ -46,7 +46,7 @@ void TestWindowTreeClientSetup::CommonInit(
     WindowManagerDelegate* window_manager_delegate) {
   window_tree_.reset(new TestWindowTree);
   window_tree_client_ = base::MakeUnique<WindowTreeClient>(
-      nullptr, window_tree_delegate, window_manager_delegate);
+      nullptr, nullptr, window_tree_delegate, window_manager_delegate);
   window_tree_->set_client(window_tree_client_.get());
 }