Separate mojo/shell into a runner and the application manager (shell)

mojo/shell/test/pingable.mojom

Index: mojo/shell/test/pingable.mojom
diff --git a/mojo/shell/test/pingable.mojom b/mojo/shell/test/pingable.mojom
deleted file mode 100644
index 74ed38d3d0cd8e820cade5e369318cb4e7ef63a4..0000000000000000000000000000000000000000
--- a/mojo/shell/test/pingable.mojom
+++ /dev/null
@@ -1,9 +0,0 @@
-// Copyright 2015 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;
-
-interface Pingable {
-  Ping(string message) => (string app_url, string connection_url, string message);
-};