Add a test for application lifecycle

mojo/shell/public/cpp/lib/application_runner.cc

Index: mojo/shell/public/cpp/lib/application_runner.cc
diff --git a/mojo/shell/public/cpp/lib/application_runner.cc b/mojo/shell/public/cpp/lib/application_runner.cc
index de4bfe9639ae47fab8696124f9a3b9bf33c7f975..3a358608c2a5b759f4e4ef65cc52d699fd3623a9 100644
--- a/mojo/shell/public/cpp/lib/application_runner.cc
+++ b/mojo/shell/public/cpp/lib/application_runner.cc
@@ -54,10 +54,10 @@ MojoResult ApplicationRunner::Run(MojoHandle shell_client_request_handle,
     else
       loop.reset(new base::MessageLoop(message_loop_type_));
 
-    ShellConnection impl(client_.get(),
-                         MakeRequest<shell::mojom::ShellClient>(
-                            MakeScopedHandle(MessagePipeHandle(
-                                shell_client_request_handle))));
+    connection_.reset(new ShellConnection(
+        client_.get(),
+        MakeRequest<shell::mojom::ShellClient>(MakeScopedHandle(
+            MessagePipeHandle(shell_client_request_handle)))));
     loop->Run();
     // It's very common for the client to cache the app and terminate on errors.
     // If we don't delete the client before the app we run the risk of the
@@ -67,6 +67,7 @@ MojoResult ApplicationRunner::Run(MojoHandle shell_client_request_handle,
     // client.
     loop.reset();
     client_.reset();
+    connection_.reset();
   }
   return MOJO_RESULT_OK;
 }
@@ -80,4 +81,8 @@ MojoResult ApplicationRunner::Run(MojoHandle shell_client_request_handle) {
   return Run(shell_client_request_handle, init_base);
 }
 
+void ApplicationRunner::DestroyShellConnection() {
+  connection_.reset();
+}
+
 }  // namespace mojo