Somewhere in the updates, Chrome stopped displaying PDFs for me, giving me a grey page. Under Options I could find no way to reenable PDF display. I finally got upset enough to search for the solution, instead of using Firefox, and I found it.

pdf files equal a blank page - Google Chrome Help

It's the tip by naveenvnair, 5th on the page. When I searched for on my system, I found three candidates:

I decided to delete the second one, which is actually a symlink to the first. I restarted chrome, clicked on a PDF link and voila, it downloaded it and by clicking on the tab corresponding to the download, I could fire up Acroread on it. You can also make that happen automatically if you are not concerned about evil PDFs taking advantage of acroread bugs, but perhaps you should leave it at a 2 step process.

PDF download in Firefox is not affected by this.

Also I suspect an Acroread update might recreate the link, so keep an eye on updates.