Don't pass empty Rectangle to PDFExtOutDevData::EndGroup(), it will
result in early return from PDFWriterImpl::drawJPGBitmap() and no
picture in the PDF.  Passing in the same Rectangle for the 3rd and 4th
parameter will avoid cropping in PDFExtOutDevData.

(regression from 677df250)

Change-Id: Icf110fe3e635319419fcacc7bc684c792a34d6ad