Handful of changes to get mus to shutdown correctly

components/mus/ws/server_window_surface.cc

 // 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 "components/mus/ws/server_window_surface.h"
 
 #include "cc/output/compositor_frame.h"
 #include "cc/quads/shared_quad_state.h"
 #include "cc/quads/surface_draw_quad.h"
 #include "components/mus/surfaces/surfaces_state.h"
@@ skipping 137 matching lines @@
     underlay_quad->SetAll(sqs, input->rect.To<gfx::Rect>(),
                           input->opaque_rect.To<gfx::Rect>(),
                           input->visible_rect.To<gfx::Rect>(),
                           input->needs_blending, underlay_surface->id());
   }
   return true;
 }
 
 void ServerWindowSurface::ReturnResources(
     const cc::ReturnedResourceArray& resources) {
-  if (!client_)
+  if (!client_ || !base::MessageLoop::current())
     return;
   client_->ReturnResources(
       mojo::Array<mojom::ReturnedResourcePtr>::From(resources));
 }
 
 void ServerWindowSurface::SetBeginFrameSource(
     cc::BeginFrameSource* begin_frame_source) {
   // TODO(tansell): Implement this.
 }
 
 }  // namespace ws
 }  // namespace mus