Quit the message loop by default in ShellConnectionLost when ApplicationRunner is used

components/mus/mus_app.cc

Index: components/mus/mus_app.cc
diff --git a/components/mus/mus_app.cc b/components/mus/mus_app.cc
index 8128d020a583e233917c31c7935c55129cddfefc..6d15e5b0144eaaf52c0584d113cf5a9d53c9a884 100644
--- a/components/mus/mus_app.cc
+++ b/components/mus/mus_app.cc
@@ -171,11 +171,6 @@ bool MandolineUIServicesApp::AcceptConnection(Connection* connection) {
   return true;
 }
 
-void MandolineUIServicesApp::ShellConnectionLost() {
-  // TODO: This should exit cleanly.
-  _exit(1);
-}
-
 void MandolineUIServicesApp::OnFirstDisplayReady() {
   PendingRequests requests;
   requests.swap(pending_requests_);