UploadDataStream now returns errors on failures

net/base/elements_upload_data_stream.h

 // 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.
 
 #ifndef NET_BASE_ELEMENTS_UPLOAD_DATA_STREAM_H_
 #define NET_BASE_ELEMENTS_UPLOAD_DATA_STREAM_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 59 matching lines @@
   void ProcessReadResult(const scoped_refptr<DrainableIOBuffer>& buf,
                          int result);
 
   std::vector<std::unique_ptr<UploadElementReader>> element_readers_;
 
   // Index of the current upload element (i.e. the element currently being
   // read). The index is used as a cursor to iterate over elements in
   // |upload_data_|.
   size_t element_index_;
 
-  // True if an error occcured during read operation.
-  bool read_failed_;
+  // Set to actual error if read fails, otherwise set to net::OK.
+  int read_error_;
 
   base::WeakPtrFactory<ElementsUploadDataStream> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(ElementsUploadDataStream);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_ELEMENTS_UPLOAD_DATA_STREAM_H_