Finally found a way to read a pdf file on LG WebOS.
Upload your document to google drive from your PC or mobile phone.
Then run the web browser at LG WebOS (TV).
Type the web address of Google Drive (https://www.google.com/drive/)
Then find your pdf document and click to open it. It is opened by Google Document Viewer automatically on yor TV.
You can read the PDF file by using the controls on the page.
This is an indirect method really to read a PDF file on your TV, but it is the only way that works for now
