Eliminate mojo::Shell client lib class

mojo/shell/public/cpp/BUILD.gn

 # 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.
 
 # GYP version: mojo/mojo_base.gyp:mojo_application_base
 source_set("cpp") {
   public_deps = [
     ":init_commandline",
     ":sources",
   ]
@@ skipping 18 matching lines @@
     "interface_factory.h",
     "interface_factory_impl.h",
     "interface_registry.h",
     "lib/application_runner.cc",
     "lib/connection_impl.cc",
     "lib/connection_impl.h",
     "lib/connector_impl.cc",
     "lib/connector_impl.h",
     "lib/interface_factory_binder.h",
     "lib/interface_registry.cc",
+    "lib/message_loop_ref.cc",
     "lib/shell_client.cc",
     "lib/shell_connection.cc",
+    "message_loop_ref.h",
     "shell.h",
     "shell_client.h",
     "shell_connection.h",
   ]
 
   deps = [
     "//base",
     "//base:i18n",
     "//mojo/message_pump",
   ]
@@ skipping 30 matching lines @@
     "//base/test:test_support",
     "//mojo/logging",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/environment",
     "//mojo/public/cpp/system",
     "//mojo/shell/public/interfaces:interfaces_cpp_sources",
   ]
 
   data_deps = []
 }