Only support seeking file streams from the beginning of the file.

net/base/upload_file_element_reader.cc

Index: net/base/upload_file_element_reader.cc
diff --git a/net/base/upload_file_element_reader.cc b/net/base/upload_file_element_reader.cc
index 56ca3b7fa3725c9992322831a9b27742b3f5e4a1..3c8aef9265432de235c2388c285713aaceae39ae 100644
--- a/net/base/upload_file_element_reader.cc
+++ b/net/base/upload_file_element_reader.cc
@@ -114,9 +114,8 @@ void UploadFileElementReader::OnOpenCompleted(
 
   if (range_offset_) {
     int seek_result = file_stream_->Seek(
-        base::File::FROM_BEGIN, range_offset_,
-        base::Bind(&UploadFileElementReader::OnSeekCompleted,
-                   weak_ptr_factory_.GetWeakPtr(), callback));
+        range_offset_, base::Bind(&UploadFileElementReader::OnSeekCompleted,
+                                  weak_ptr_factory_.GetWeakPtr(), callback));
     DCHECK_GT(0, seek_result);
     if (seek_result != ERR_IO_PENDING)
       callback.Run(seek_result);