desktop: disable Chrome built-in PDF viewer

Chrome's PDF viewer has a tendency to crop PDFs when printing,
especially if they're not formatted for exactly US letter size (like
with many scanned documents, etc.).

I've noticed this with my own documents, and also helped a lot of people
in the past couple weeks who experienced this problem (almost always
because they were trying to print PDFs of scanned pages from bSpace).

Evince defaults to "Shrink to Printable Area" and "Auto Rotate &
Center", which are sane defaults and a much better choice for most
people.