Temporarily add logging of results messages. (#2314)

* Temporarily add logging of results messages.

This will give us visibility of the message format required to report
results from builders from dart-internal.

* Address comments.
diff --git a/app_dart/lib/src/request_handlers/postsubmit_luci_subscription.dart b/app_dart/lib/src/request_handlers/postsubmit_luci_subscription.dart
index 50f178d..550dc8c 100644
--- a/app_dart/lib/src/request_handlers/postsubmit_luci_subscription.dart
+++ b/app_dart/lib/src/request_handlers/postsubmit_luci_subscription.dart
@@ -52,10 +52,12 @@
     final String data = message.data!;
     BuildPushMessage buildPushMessage;
     try {
-      buildPushMessage =
-          BuildPushMessage.fromJson(json.decode(String.fromCharCodes(base64.decode(data))) as Map<String, dynamic>);
+      final String decodedData = String.fromCharCodes(base64.decode(data));
+      buildPushMessage = BuildPushMessage.fromJson(json.decode(decodedData) as Map<String, dynamic>);
+      log.info('Result message from base64: $decodedData');
     } on FormatException {
       buildPushMessage = BuildPushMessage.fromJson(json.decode(data) as Map<String, dynamic>);
+      log.info('Result message: $data');
     }
     log.fine(buildPushMessage.userData);
     log.fine('Updating buildId=${buildPushMessage.build?.id} for result=${buildPushMessage.build?.result}');