[BlobStorage] Better net error reporting for pre-broken blobs

storage/browser/blob/blob_url_request_job.cc

 // Copyright (c) 2012 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 "storage/browser/blob/blob_url_request_job.h"
 
 #include <stdint.h>
 
 #include <algorithm>
 #include <limits>
@@ skipping 144 matching lines @@
   if (request()->method() != "GET") {
     NotifyFailure(net::ERR_METHOD_NOT_SUPPORTED);
     return;
   }
 
   // If the blob data is not present, bail out.
   if (!blob_handle_) {
     NotifyFailure(net::ERR_FILE_NOT_FOUND);
     return;
   }
+  if (blob_reader_->net_error()) {
+    NotifyFailure(blob_reader_->net_error());
+    return;
+  }
 
   TRACE_EVENT_ASYNC_BEGIN1("Blob", "BlobRequest::CountSize", this, "uuid",
                            blob_handle_->uuid());
   BlobReader::Status size_status = blob_reader_->CalculateSize(base::Bind(
       &BlobURLRequestJob::DidCalculateSize, weak_factory_.GetWeakPtr()));
   switch (size_status) {
     case BlobReader::Status::NET_ERROR:
       NotifyFailure(blob_reader_->net_error());
       return;
     case BlobReader::Status::IO_PENDING:
@@ skipping 139 matching lines @@
 
   response_info_.reset(new net::HttpResponseInfo());
   response_info_->headers = headers;
   if (blob_reader_)
     response_info_->metadata = blob_reader_->side_data();
 
   NotifyHeadersComplete();
 }
 
 }  // namespace storage