Add a startup benchmark and rudimentary scripts for running benchmarks.

benchmarks/startup/startup.cc

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <stdlib.h>
+
+#include "mojo/public/c/system/main.h"
+
+MojoResult MojoMain(MojoHandle shell_handle) {
+  // Terminate the process as soon as we reach the application entrypoint. The
+  // testing script will instruct the shell to load this application and
+  // measure the execution time, which reflects the startup performance.
+  exit(0);
+  return MOJO_RESULT_OK;
+}