net: Fix a regression that broke file uploading with http authentication

net/base/upload_data.cc

Index: net/base/upload_data.cc
diff --git a/net/base/upload_data.cc b/net/base/upload_data.cc
index 71d77ae807a102ae0b5edf64a7184269ddabf10e..b13e9091e8cb0051caeb26a516ba1cd806f600d0 100644
--- a/net/base/upload_data.cc
+++ b/net/base/upload_data.cc
@@ -114,6 +114,20 @@ uint64 UploadData::Element::BytesRemaining() {
   return GetContentLength() - offset_;
 }
 
+void UploadData::Element::ResetOffset() {
+  offset_ = 0;
+
+  // Delete the file stream if already opened, so we can reread the file from
+  // the beginning.
+  if (file_stream_) {
+    // Temporarily allow until fix: http://crbug.com/72001.
+    base::ThreadRestrictions::ScopedAllowIO allow_io;
+    file_stream_->CloseSync();
+    delete file_stream_;
+    file_stream_ = NULL;
+  }
+}
+
 FileStream* UploadData::Element::OpenFileStream() {
   scoped_ptr<FileStream> file(new FileStream(NULL));
   int64 rv = file->OpenSync(