[Media Router] Make MRUIService dispose its dependencies on MRMojoImpl in Shutdown()

chrome/browser/media/router/media_router_ui_service.cc

 // 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.
 
 #include "chrome/browser/media/router/media_router_ui_service.h"
 
 #include "chrome/browser/media/router/media_router_feature.h"
 #include "chrome/browser/media/router/media_router_ui_service_factory.h"
 #include "chrome/browser/profiles/profile.h"
 
 namespace media_router {
 
 MediaRouterUIService::MediaRouterUIService(Profile* profile)
-    : action_controller_(profile) {}
+    : action_controller_(new MediaRouterActionController(profile)) {}
 
 MediaRouterUIService::~MediaRouterUIService() {}
 
+void MediaRouterUIService::Shutdown() {
+  action_controller_.reset();
+}
+
 // static
 MediaRouterUIService* MediaRouterUIService::Get(Profile* profile) {
   return MediaRouterUIServiceFactory::GetForBrowserContext(profile);
 }
 
 MediaRouterActionController* MediaRouterUIService::action_controller() {
-  return &action_controller_;
+  return action_controller_.get();
 }
 
 }  // namespace media_router