Do more on the web, with a fast and secure browser!
Download Opera browser with:
When using Save as PDF function in Opera, page url is not stored anywhere within the generated PDF document. Printing puts it in the footer, but result is not as nice as single-page layout that Save as PDF offers. Can url be put into Title or Subject fields of PDF's metadata?
PageTitle - PageURL in Title sounds good. If page URL is stored in a custom field, different PDF readers might not display that field anywhere. While Subject field is not used as often, it is a part of the PDF specification (Document Information Dictionary) and its use does not fall far from the tree if we say that the subject of the document is the URL from which PDF is saved from. 
As for the Chromium's PDF viewer UI in general, instead of just handling one specific field, it would be better to display all properties from PDF's Document Information Dictionary. This way it doesn't matter if the URL is in a custom or a standard field.