Add a test for application lifecycle

mojo/shell/tests/lifecycle/lifecycle_unittest.mojom

+// 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.
+
+module mojo.shell.test.mojom;
+
+// An interface implemented by an application exposing different ways for the
+// application to "shut down" from the caller and shell's perspective.
+interface LifecycleControl {
+  // Method for ping-pong acknowledgement.
+  Ping() => ();
+
+  // Perform any normal cleanup and shut down normally.
+  GracefulQuit();
+
+  // Crash immediately and leave the shell and clients to deal with the
+  // consequences.
+  Crash();
+
+  // Not actually a shutdown from the client's perspective, but the Shell is no
+  // longer tracking this application.
+  CloseShellConnection();
+};