Introduce ParallelDownloadJob.

content/browser/download/download_create_info.h

Index: content/browser/download/download_create_info.h
diff --git a/content/browser/download/download_create_info.h b/content/browser/download/download_create_info.h
index c0c7f17dc190ae8f209f13d7127d0d0de7b4bdd9..174fded169ade9ae4f99c689987daa6c18aba238 100644
--- a/content/browser/download/download_create_info.h
+++ b/content/browser/download/download_create_info.h
@@ -110,6 +110,9 @@ struct CONTENT_EXPORT DownloadCreateInfo {
   // For continuing a download, the ETag of the file.
   std::string etag;
 
+  // If "Accept-Ranges:bytes" header presents in the response header.
+  bool accept_range;
+
  private:
   DISALLOW_COPY_AND_ASSIGN(DownloadCreateInfo);
 };