Revert of service worker: use 200 OK for update requests even in the no update case

content/browser/service_worker/service_worker_write_to_cache_job.h

Index: content/browser/service_worker/service_worker_write_to_cache_job.h
diff --git a/content/browser/service_worker/service_worker_write_to_cache_job.h b/content/browser/service_worker/service_worker_write_to_cache_job.h
index 152dd8402509af10d33e874a12c51db56502d0ae..8cb483cb41c20ba96c8b220374cff32513f7a664 100644
--- a/content/browser/service_worker/service_worker_write_to_cache_job.h
+++ b/content/browser/service_worker/service_worker_write_to_cache_job.h
@@ -40,9 +40,8 @@
 // incumbent script is detected. The incumbent script is progressively compared
 // with the new script as it is read from network. Once a change is detected,
 // everything that matched is copied to disk, and from then on the script is
-// written as it continues to be read from network. If the scripts are
-// identical, the resulting ServiceWorkerScriptCacheMap's main script status is
-// set to kIdenticalScriptError.
+// written as it continues to be read from network. If the scripts were
+// identical, the job fails so the worker can be discarded.
 class CONTENT_EXPORT ServiceWorkerWriteToCacheJob
     : public net::URLRequestJob,
       public net::URLRequest::Delegate {
@@ -55,10 +54,6 @@
                                int extra_load_flags,
                                int64_t resource_id,
                                int64_t incumbent_resource_id);
-
-  // The error code used when update fails because the new
-  // script is byte-by-byte identical to the incumbent script.
-  const static net::Error kIdenticalScriptError;
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ServiceWorkerContextRequestHandlerTest,