Add rudimentary mash shelf functionality.

mash/system_ui/main.cc

Index: mash/system_ui/main.cc
diff --git a/mash/system_ui/main.cc b/mash/system_ui/main.cc
deleted file mode 100644
index 0c5832bea3747036a0145bc7a583b62099762ddb..0000000000000000000000000000000000000000
--- a/mash/system_ui/main.cc
+++ /dev/null
@@ -1,12 +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.
-
-#include "mash/system_ui/system_ui.h"
-#include "mojo/public/c/system/main.h"
-#include "mojo/shell/public/cpp/application_runner.h"
-
-MojoResult MojoMain(MojoHandle shell_handle) {
-  mojo::ApplicationRunner runner(new mash::system_ui::SystemUI);
-  return runner.Run(shell_handle);
-}