Fix mojo::shell::Context shutdown.

shell/in_process_dynamic_service_runner_unittest.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 "shell/context.h"
 #include "shell/in_process_dynamic_service_runner.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace mojo {
 namespace shell {
 
 TEST(InProcessDynamicServiceRunnerTest, NotStarted) {
   Context context;
   base::MessageLoop loop;
   context.Init();
   InProcessDynamicServiceRunner runner(&context);
+  context.Shutdown();
   // Shouldn't crash or DCHECK on destruction.
 }
 
 }  // namespace shell
 }  // namespace mojo