Assume stoping vm_concierge succeeds if we get an empty response

Currently, we assume that debugd sends back a boolean success/fail
value in the response when asked to shutdown vm_concierge, but in fact
the response is empty, resulting in spurious error messages. This CL
changes this behaviour to assume success when receving any response,
including an empty one.

Bug: 900841
Change-Id: I04682973c6dc9d190d43c1626c9b4e05cfa35484
Reviewed-on: https://chromium-review.googlesource.com/c/1312140
Commit-Queue: Fergus Dall <sidereal@google.com>
Reviewed-by: Ryo Hashimoto <hashimoto@chromium.org>
Reviewed-by: Nicholas Verne <nverne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606284}

chromeos/dbus/debug_daemon_client.cc

@@ -734,12 +734,9 @@ class DebugDaemonClientImpl : public DebugDaemonClient {
   }
 
   void OnStopConcierge(ConciergeCallback callback, dbus::Response* response) {
-    bool result = false;
-    dbus::MessageReader reader(response);
-    if (response) {
-      reader.PopBool(&result);
-    }
-    std::move(callback).Run(result);
+    // Debugd just sends back an empty response, so we just check if
+    // the response exists
+    std::move(callback).Run(response != nullptr);
   }
 
   void OnSetRlzPingSent(SetRlzPingSentCallback callback,