Service Worker: Improve error messages from register().

content/browser/service_worker/service_worker_registration_status.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/service_worker/service_worker_registration_status.h"
 
 #include "base/logging.h"
 #include "base/strings/utf_string_conversions.h"
 
 namespace content {
 
 using blink::WebServiceWorkerError;
 
 void GetServiceWorkerRegistrationStatusResponse(
     ServiceWorkerStatusCode status,
+    const std::string& status_message,
     blink::WebServiceWorkerError::ErrorType* error_type,
     base::string16* message) {
   *error_type = WebServiceWorkerError::ErrorTypeUnknown;
-  *message = base::ASCIIToUTF16(ServiceWorkerStatusToString(status));
+  if (!status_message.empty())
+    *message = base::UTF8ToUTF16(status_message);
+  else
+    *message = base::ASCIIToUTF16(ServiceWorkerStatusToString(status));
   switch (status) {
     case SERVICE_WORKER_OK:
       NOTREACHED() << "Calling this when status == OK is not allowed";
       return;
 
     case SERVICE_WORKER_ERROR_START_WORKER_FAILED:
     case SERVICE_WORKER_ERROR_INSTALL_WORKER_FAILED:
       *error_type = WebServiceWorkerError::ErrorTypeInstall;
       return;
 
@@ skipping 21 matching lines @@
     case SERVICE_WORKER_ERROR_EVENT_WAITUNTIL_REJECTED:
       // Unexpected, or should have bailed out before calling this, or we don't
       // have a corresponding blink error code yet.
       break;  // Fall through to NOTREACHED().
   }
   NOTREACHED() << "Got unexpected error code: "
                << status << " " << ServiceWorkerStatusToString(status);
 }
 
 }  // namespace content