So. I installed Acrobet. I generally like it for dealing with large PDF files. However, since I've installed it, is insists on opening every time I download a PDF from Chrome. I'm sure this is a silly-ass setting somewhere, but I've not found it.
The exact behavior is that I look at the PDF in Chrome, then "Save As" to save it. At that point the Adobe Acrobat takes over.
chrome://plugins/ is no help. See screenshot attached: