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

chrome/browser/media/router/media_router_ui_service.h

Index: chrome/browser/media/router/media_router_ui_service.h
diff --git a/chrome/browser/media/router/media_router_ui_service.h b/chrome/browser/media/router/media_router_ui_service.h
index 5be5daa22444d65eb74ce1955a26c827a5cc1738..d1462a6cce7a536762b6b21463bc99ec14fa10c8 100644
--- a/chrome/browser/media/router/media_router_ui_service.h
+++ b/chrome/browser/media/router/media_router_ui_service.h
@@ -21,6 +21,9 @@ class MediaRouterUIService : public KeyedService {
   explicit MediaRouterUIService(Profile* profile);
   ~MediaRouterUIService() override;
 
+  // KeyedService:
+  void Shutdown() override;
+
   static MediaRouterUIService* Get(Profile* profile);
 
   virtual MediaRouterActionController* action_controller();
@@ -28,7 +31,7 @@ class MediaRouterUIService : public KeyedService {
  private:
   friend class MediaRouterUIBrowserTest;
 
-  MediaRouterActionController action_controller_;
+  std::unique_ptr<MediaRouterActionController> action_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaRouterUIService);
 };