Revert of Quit the message loop by default in ShellConnectionLost when ApplicationRunner is used (patchset #2 id:20001 of https://codereview.chromium.org/1819063002/ )

Reason for revert:
Looks like to made the mojo_apptests go red. I think this is also making MUS tests fail?

https://build.chromium.org/p/chromium.linux/builders/Linux%20Tests/builds/39128

Original issue's description:
> Quit the message loop by default in ShellConnectionLost when ApplicationRunner is used
>
> This was originally at https://codereview.chromium.org/1814223002/ , but Ben is out and
> I need this for tests, so I'm taking over.
>
> BUG=none
> TEST=covered by tests
> TBR=ben@chromium.org
> R=ben@chromium.org
>
> Committed: https://crrev.com/a50f9840749052fbdec087a304548217cc6fd00b
> Cr-Commit-Position: refs/heads/master@{#382389}

TBR=ben@chromium.org,sky@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=none

Review URL: https://codereview.chromium.org/1821913002

Cr-Commit-Position: refs/heads/master@{#382460}

1 files changed, 6 insertions, 0 deletions

diff --git a/mojo/shell/tests/connect/connect_test_package.cc b/mojo/shell/tests/connect/connect_test_package.cc
index 1458e65..c5a1a07 100644
--- a/mojo/shell/tests/connect/connect_test_package.cc
+++ b/mojo/shell/tests/connect/connect_test_package.cc
@@ -184,6 +184,12 @@ class ConnectTestShellClient
     connection->AddInterface<test::mojom::ConnectTestService>(this);
     return true;
   }
+  void ShellConnectionLost() override {
+    if (base::MessageLoop::current() &&
+        base::MessageLoop::current()->is_running()) {
+      base::MessageLoop::current()->QuitWhenIdle();
+    }
+  }
 
   // InterfaceFactory<mojom::ShellClientFactory>:
   void Create(Connection* connection,