Handful of changes to get mus to shutdown correctly

components/mus/mus_app.cc

 // 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.
 
 #include "components/mus/mus_app.h"
 
 #include <set>
 
 #include "base/memory/weak_ptr.h"
 #include "base/stl_util.h"
@@ skipping 51 matching lines @@
 };
 
 struct MandolineUIServicesApp::UserState {
   scoped_ptr<ws::WindowTreeFactory> window_tree_factory;
   scoped_ptr<ws::WindowTreeHostFactory> window_tree_host_factory;
 };
 
 MandolineUIServicesApp::MandolineUIServicesApp() {}
 
 MandolineUIServicesApp::~MandolineUIServicesApp() {
+  // Destroy |window_server_| first, since it depends on |event_source_|.
+  // WindowServer (or more correctly its Displays) may have state that needs to
+  // be destroyed before GpuState as well.
+  window_server_.reset();
+
   if (platform_display_init_params_.gpu_state)
     platform_display_init_params_.gpu_state->StopThreads();
-  // Destroy |window_server_| first, since it depends on |event_source_|.
-  window_server_.reset();
 }
 
 void MandolineUIServicesApp::InitializeResources(mojo::Connector* connector) {
   if (ui::ResourceBundle::HasSharedInstance())
     return;
 
   std::set<std::string> resource_paths;
   resource_paths.insert(kResourceFileStrings);
   resource_paths.insert(kResourceFile100);
   resource_paths.insert(kResourceFile200);
@@ skipping 88 matching lines @@
 }
 
 void MandolineUIServicesApp::OnFirstDisplayReady() {
   PendingRequests requests;
   requests.swap(pending_requests_);
   for (auto& request : requests)
     Create(request->connection, std::move(*request->wtf_request));
 }
 
 void MandolineUIServicesApp::OnNoMoreDisplays() {
-  base::MessageLoop::current()->QuitWhenIdle();
+  // We may get here from the destructor, in which case there is no messageloop.
+  if (base::MessageLoop::current())
+    base::MessageLoop::current()->QuitWhenIdle();
 }
 
 scoped_ptr<ws::WindowTreeBinding>
 MandolineUIServicesApp::CreateWindowTreeBindingForEmbedAtWindow(
     ws::WindowServer* window_server,
     ws::WindowTree* tree,
     mojom::WindowTreeRequest tree_request,
     mojom::WindowTreeClientPtr client) {
   return make_scoped_ptr(new ws::DefaultWindowTreeBinding(
       tree, window_server, std::move(tree_request), std::move(client)));
@@ skipping 59 matching lines @@
   user_state->window_tree_host_factory->AddBinding(std::move(request));
 }
 
 void MandolineUIServicesApp::Create(mojo::Connection* connection,
                                     mojom::GpuRequest request) {
   DCHECK(platform_display_init_params_.gpu_state);
   new GpuImpl(std::move(request), platform_display_init_params_.gpu_state);
 }
 
 }  // namespace mus