Allow the initial request to take over failed parallel requests.

content/browser/download/download_file_impl.h

Index: content/browser/download/download_file_impl.h
diff --git a/content/browser/download/download_file_impl.h b/content/browser/download/download_file_impl.h
index 41db8d9353019f115644a72de9285d8a01b3e3f4..c6a4ae20e7c7febea6ef04e71e3de130913ae9f9 100644
--- a/content/browser/download/download_file_impl.h
+++ b/content/browser/download/download_file_impl.h
@@ -213,6 +213,14 @@ class CONTENT_EXPORT DownloadFileImpl : public DownloadFile {
   // Otherwise, return the current file size.
   int64_t TotalBytesReceived() const;
 
+  // Helper method to handle stream error
+  void HandleStreamError(SourceStream* source_stream,
+                         DownloadInterruptReason reason);
+
+  // Given a SourceStream object, returns its neighbor that preceds it if
+  // SourceStreams are ordered by their offsets
+  SourceStream* FindPrecedingNeighbor(SourceStream* source_stream);
+
   net::NetLogWithSource net_log_;
 
   // The base file instance.