Add RunMainApplication()/TerminateMainApplication() for use in MojoMain().

examples/spinning_cube/spinning_cube_app.cc

Index: examples/spinning_cube/spinning_cube_app.cc
diff --git a/examples/spinning_cube/spinning_cube_app.cc b/examples/spinning_cube/spinning_cube_app.cc
index eac07b2785c7c33819998afb0696929d5094d2e2..a1fc4a7ab755e2565af87750a5bee16fd1317ea2 100644
--- a/examples/spinning_cube/spinning_cube_app.cc
+++ b/examples/spinning_cube/spinning_cube_app.cc
@@ -95,5 +95,5 @@ class SpinningCubeApp : public mojo::ApplicationImplBase,
 
 MojoResult MojoMain(MojoHandle application_request) {
   examples::SpinningCubeApp spinning_cube_app;
-  return mojo::RunApplication(application_request, &spinning_cube_app);
+  return mojo::RunMainApplication(application_request, &spinning_cube_app);
 }