Add a Mojo example apptest that runs in mojo_shell.

mojo/examples/apptest/example_client_application.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 "mojo/examples/apptest/example_client_application.h"
+
+#include "mojo/examples/apptest/example_client_impl.h"
+
+namespace mojo {
+
+ExampleClientApplication::ExampleClientApplication() {}
+
+ExampleClientApplication::~ExampleClientApplication() {}
+
+void ExampleClientApplication::Initialize(ApplicationImpl* app) {}
+
+// static
+ApplicationDelegate* ApplicationDelegate::Create() {
+  return new ExampleClientApplication();
+}
+
+}  // namespace mojo