mash: Fix shutdown crashes by tearing down ServiceContext before message loop

chrome/app/mash/mash_runner.h

 // Copyright 2016 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.
 
 #ifndef CHROME_APP_MASH_MASH_RUNNER_H_
 #define CHROME_APP_MASH_MASH_RUNNER_H_
 
 #include <memory>
 
 #include "base/macros.h"
 #include "services/service_manager/public/interfaces/service.mojom.h"
 
-namespace service_manager {
-class ServiceContext;
-}
-
 // Responsible for running mash, both child and main processes.
 class MashRunner {
  public:
   MashRunner();
   ~MashRunner();
 
   // Returns 0 if the process was initialized correctly, or error code on
   // failure.
   int Run();
 
  private:
   // Runs the main process, including the service manager. Returns the exit
   // value for the process.
   int RunMain();
 
   // Runs a background service manager in the main process. Returns the exit
   // value for the process.
   int RunServiceManagerInMain();
 
   // Returns 0 if the child process was initialized correctly, or error code on
   // failure.
   int RunChild();
 
   void StartChildApp(service_manager::mojom::ServiceRequest service_request);
 
-  // Context for service manager in the main process.
-  std::unique_ptr<service_manager::ServiceContext> context_;
-
   DISALLOW_COPY_AND_ASSIGN(MashRunner);
 };
 
 // Called during chrome --mash startup instead of ContentMain().
 int MashMain();
 
 // Called if the command line isn't mash to potentially wait for a debugger
 // to attach.
 void WaitForMashDebuggerIfNecessary();
 
 #endif  // CHROME_APP_MASH_MASH_RUNNER_H_