Fix issues and feature polishing for parallel download.

content/browser/download/download_request_core.cc

Index: content/browser/download/download_request_core.cc
diff --git a/content/browser/download/download_request_core.cc b/content/browser/download/download_request_core.cc
index b3957be4143fcaab23bae233b85b4511a0ca94fb..53954e1384fca21078b1509223d3a2630b8fbec7 100644
--- a/content/browser/download/download_request_core.cc
+++ b/content/browser/download/download_request_core.cc
@@ -280,6 +280,7 @@ DownloadRequestCore::CreateDownloadCreateInfo(DownloadInterruptReason result) {
   create_info->result = result;
   create_info->download_id = download_id_;
   create_info->offset = create_info->save_info->offset;
+  create_info->length = create_info->save_info->length;
   return create_info;
 }