Shows the error message while fetching the SW script in the DevTools console.

content/browser/service_worker/embedded_worker_instance.h

Index: content/browser/service_worker/embedded_worker_instance.h
diff --git a/content/browser/service_worker/embedded_worker_instance.h b/content/browser/service_worker/embedded_worker_instance.h
index 1da7e1370ccaa2d392e4c0e4e37f2abb7ab0a176..9356bb531f0510aca376961a69e14e50e48f1f6a 100644
--- a/content/browser/service_worker/embedded_worker_instance.h
+++ b/content/browser/service_worker/embedded_worker_instance.h
@@ -23,6 +23,7 @@
 #include "content/browser/service_worker/service_worker_metrics.h"
 #include "content/common/content_export.h"
 #include "content/common/service_worker/service_worker_status_code.h"
+#include "content/public/common/console_message_level.h"
 #include "url/gurl.h"
 
 // Windows headers will redefine SendMessage.
@@ -180,6 +181,10 @@ class CONTENT_EXPORT EmbeddedWorkerInstance {
   // created. Not called for import scripts.
   void OnURLJobCreatedForMainScript();
 
+  // Add message to the devtools console.
+  void AddMessageToConsole(ConsoleMessageLevel level,
+                           const std::string& message);
+
   static std::string StatusToString(Status status);
   static std::string StartingPhaseToString(StartingPhase phase);