Remove mojo/shell and (most) service implementations

mojo/shell/external_application_registrar.mojom

Index: mojo/shell/external_application_registrar.mojom
diff --git a/mojo/shell/external_application_registrar.mojom b/mojo/shell/external_application_registrar.mojom
deleted file mode 100644
index db76aec4526fe0f100b257a683961f6d1017d318..0000000000000000000000000000000000000000
--- a/mojo/shell/external_application_registrar.mojom
+++ /dev/null
@@ -1,18 +0,0 @@
-// 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.
-
-import "mojo/public/interfaces/application/shell.mojom"
-
-module mojo {
-
-// This interface allows applications running outside the auspices of a Shell
-// to request registration at the given application_url.
-// The shell implementing this interface will make the calling application
-// available to other apps at that URL and bind the provided Shell& to
-// an impl capable of servicing the external application's connection requests.
-interface ExternalApplicationRegistrar {
-  Register(string application_url, Shell& shell) => ();
-};
-
-}