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

content/common/service_worker/embedded_worker_messages.h

 // Copyright 2014 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.
 
 // Message definition file, included multiple times, hence no include guard.
 
 #include <stdint.h>
 
 #include <string>
 
 #include "content/common/service_worker/embedded_worker_settings.h"
+#include "content/public/common/console_message_level.h"
 #include "content/public/common/web_preferences.h"
 #include "ipc/ipc_message.h"
 #include "ipc/ipc_message_macros.h"
 #include "ipc/ipc_param_traits.h"
 #include "url/gurl.h"
 
 #undef IPC_MESSAGE_EXPORT
 #define IPC_MESSAGE_EXPORT CONTENT_EXPORT
 
 #define IPC_MESSAGE_START EmbeddedWorkerMsgStart
@@ skipping 33 matching lines @@
 
 // Browser -> Renderer message to resume a worker that has been started
 // with the pause_after_download option.
 IPC_MESSAGE_CONTROL1(EmbeddedWorkerMsg_ResumeAfterDownload,
                      int /* embedded_worker_id */)
 
 // Browser -> Renderer message to stop (terminate) the embedded worker.
 IPC_MESSAGE_CONTROL1(EmbeddedWorkerMsg_StopWorker,
                      int /* embedded_worker_id */)
 
+// Browser -> Renderer message to add message to the devtools console.
+IPC_MESSAGE_CONTROL3(EmbeddedWorkerMsg_AddMessageToConsole,
+                     int /* embedded_worker_id */,
+                     content::ConsoleMessageLevel /* level */,
+                     std::string /* message */)
+
 // Renderer -> Browser message to indicate that the worker is ready for
 // inspection.
 IPC_MESSAGE_CONTROL1(EmbeddedWorkerHostMsg_WorkerReadyForInspection,
                      int /* embedded_worker_id */)
 
 // Renderer -> Browser message to indicate that the worker has loaded the
 // script.
 IPC_MESSAGE_CONTROL1(EmbeddedWorkerHostMsg_WorkerScriptLoaded,
                      int /* embedded_worker_id */)
 
@@ skipping 42 matching lines @@
 // for this for easier cross-thread message dispatching.
 
 #undef IPC_MESSAGE_START
 #define IPC_MESSAGE_START EmbeddedWorkerContextMsgStart
 
 // Browser -> Renderer message to send message.
 IPC_MESSAGE_CONTROL3(EmbeddedWorkerContextMsg_MessageToWorker,
                      int /* thread_id */,
                      int /* embedded_worker_id */,
                      IPC::Message /* message */)