ServiceWorker: Change worker script fetch error code(1/3).

public/platform/WebServiceWorkerError.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 24 matching lines @@
 
 namespace blink {
 
 struct WebServiceWorkerError {
     enum ErrorType {
         ErrorTypeDisabled = 0,
         ErrorTypeAbort,
         ErrorTypeSecurity,
         ErrorTypeInstall,
         ErrorTypeActivate,
+        ErrorTypeNetwork,
         ErrorTypeNotFound,
         ErrorTypeUnknown,
         ErrorTypeLast = ErrorTypeUnknown
     };
 
     WebServiceWorkerError(ErrorType errorType, const WebString& message)
         : errorType(errorType), message(message) { }
 
     ErrorType errorType;
     WebString message;
 };
 
 } // namespace blink
 
 #endif