Glue parallel download job and download file together.

content/browser/download/mock_download_file.cc

Index: content/browser/download/mock_download_file.cc
diff --git a/content/browser/download/mock_download_file.cc b/content/browser/download/mock_download_file.cc
index e8abcf2db07dccaad8cb6f4b555ff25ecea91b0f..2f10f54cf6f3a35ee3bf6e4437415b5c54925870 100644
--- a/content/browser/download/mock_download_file.cc
+++ b/content/browser/download/mock_download_file.cc
@@ -29,10 +29,11 @@ MockDownloadFile::~MockDownloadFile() {
 
 void MockDownloadFile::AddByteStream(
     std::unique_ptr<ByteStreamReader> stream_reader,
-    int64_t offset) {
+    int64_t offset,
+    int64_t length) {
   // Gmock currently can't mock method that takes move-only parameters,
   // delegate the EXPECT_CALL count to |DoAddByteStream|.
-  DoAddByteStream(stream_reader.get(), offset);
+  DoAddByteStream(stream_reader.get(), offset, length);
 }
 
 }  // namespace content