net: Make UploadDataStream::Init() asynchronous.

net/base/upload_element_reader.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 "net/base/upload_element_reader.h"
 
 #include "base/logging.h"
+#include "net/base/net_errors.h"
 #include "net/base/upload_bytes_element_reader.h"
 #include "net/base/upload_element.h"
 #include "net/base/upload_file_element_reader.h"
 
 namespace net {
 
 // static
 UploadElementReader* UploadElementReader::Create(const UploadElement& element) {
   UploadElementReader* reader = NULL;
   switch (element.type()) {
     case UploadElement::TYPE_BYTES:
       reader = new UploadBytesElementReader(element.bytes(),
                                             element.bytes_length());
       break;
     case UploadElement::TYPE_FILE:
       reader = new UploadFileElementReader(
           element.file_path(),
           element.file_range_offset(),
           element.file_range_length(),
           element.expected_file_modification_time());
       break;
   }
   DCHECK(reader);
   return reader;
 }
 
+int UploadElementReader::InitSync() {
+  NOTREACHED() << "This instance does not support InitSync().";
+  return ERR_NOT_IMPLEMENTED;
+}
+
 bool UploadElementReader::IsInMemory() const {
   return false;
 }
 
 }  // namespace net