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

mojo/shell/tests/connect/connect_test_app.cc

Index: mojo/shell/tests/connect/connect_test_app.cc
diff --git a/mojo/shell/tests/connect/connect_test_app.cc b/mojo/shell/tests/connect/connect_test_app.cc
index 4180763f0fff9b2ed8a3c7593c51769fa132eaa7..342e14d7deb8a117ababd45fb22eccce591dbda5 100644
--- a/mojo/shell/tests/connect/connect_test_app.cc
+++ b/mojo/shell/tests/connect/connect_test_app.cc
@@ -78,6 +78,12 @@
     caller_->ConnectionAccepted(std::move(state));
 
     return true;
+  }
+  void ShellConnectionLost() override {
+    if (base::MessageLoop::current() &&
+        base::MessageLoop::current()->is_running()) {
+      base::MessageLoop::current()->QuitWhenIdle();
+    }
   }
 
   // InterfaceFactory<test::mojom::ConnectTestService>: