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

mojo/shell/background/tests/test_service.cc

Index: mojo/shell/background/tests/test_service.cc
diff --git a/mojo/shell/background/tests/test_service.cc b/mojo/shell/background/tests/test_service.cc
index d030a814340064955baf1723ebfd40f547807fb2..040f840f3f5676e76eedfa3882bcf5c50fa01ab6 100644
--- a/mojo/shell/background/tests/test_service.cc
+++ b/mojo/shell/background/tests/test_service.cc
@@ -25,8 +25,8 @@ class TestClient : public ShellClient,
     connection->AddInterface(this);
     return true;
   }
-  void ShellConnectionLost() override {
-    base::MessageLoop::current()->QuitWhenIdle();
+  bool ShellConnectionLost() {
+    return true;
   }
 
   // InterfaceFactory<mojom::TestService>: