Add simplistic screenlock application.

mash/screenlock/main.cc

Index: mash/screenlock/main.cc
diff --git a/mash/screenlock/main.cc b/mash/screenlock/main.cc
new file mode 100644
index 0000000000000000000000000000000000000000..23b307da6f9d11d2617b46ae422f17cab72d1bc0
--- /dev/null
+++ b/mash/screenlock/main.cc
@@ -0,0 +1,12 @@
+// Copyright 2016 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 "mash/screenlock/screenlock.h"
+#include "mojo/public/c/system/main.h"
+#include "mojo/shell/public/cpp/application_runner.h"
+
+MojoResult MojoMain(MojoHandle shell_handle) {
+  mojo::ApplicationRunner runner(new mash::screenlock::Screenlock);
+  return runner.Run(shell_handle);
+}