mojo: kill app_thread before unloading main app library and add tests

mojo/shell/context.cc

 // Copyright 2013 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 "mojo/shell/context.h"
 
 #include "build/build_config.h"
 #include "base/command_line.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_vector.h"
@@ skipping 132 matching lines @@
   service_manager_.SetLoaderForURL(
       scoped_ptr<ServiceLoader>(
           new BackgroundServiceLoader(
               scoped_ptr<ServiceLoader>(new NetworkServiceLoader()),
               "network_service",
               base::MessageLoop::TYPE_IO)),
       GURL("mojo:mojo_network_service"));
 #endif
 }
 
-Context::~Context() {
+void Context::Shutdown() {
   // mojo_view_manager uses native_viewport. Destroy mojo_view_manager first so
   // that there aren't shutdown ordering issues. Once native viewport service is
   // moved into its own process this can likely be nuked.
 #if defined(USE_AURA)
   service_manager_.SetLoaderForURL(
       scoped_ptr<ServiceLoader>(),
       GURL("mojo:mojo_view_manager"));
 #endif
   service_manager_.set_default_loader(scoped_ptr<ServiceLoader>());
+  service_manager_.TerminateShellConnections();
+}
+
+Context::~Context() {
+  Shutdown();
 }
 
 }  // namespace shell
 }  // namespace mojo