Cascade shutdown of instances

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();
 };
+
+// Implemented by an app that connects to another app, thereby creating an
+// instance for it in the shell.
+interface Parent {
+  // Connects to another app and runs the callback when that app has acked a
+  // Ping.
+  ConnectToChild() => ();
+  Quit();
+};