Currently when you export using the portfolio API to Google Drive any files sent are not converted and so are stored in Drive in their original format.
This may be suitable for some situations, but in most plugins (forum etc) html is sent and thus you end up with a pointless 'raw' html file in your Drive rather than something converted to a native Google Doc.
Prior to the updates to googleapi.php to support OAuth 2.0 the Google Docs export used to convert these html files to native format.
/portfolio/googledocs/lib.php calls /lib/googleapi.php send_file() method when exporting to Google Drive - send_file() uses a url with param convert=false (so if it were convert=true file would be converted to native format).
Ideally there should be some way that either the decision to convert the file or not is automatic (or possibly settings based, using filetype), or that the plugin calling the portfolio export can request the conversion in some way.