Using prefetch or prerender
Per Brad's answer, PHP is setting the cache control headers on the start of a new user session. 

If you want to override this, Craft provides the {% header %} tag where you can set your own headers. Whether or not that affects Chrome, I couldn't say.

One other thing to note is cookies. This page mentions "prerendered or prefetched [pages] may set and read their own cookies as if you had visited them before -- even if you don’t visit the prerendered or prefetched pages after all" which seems to imply it'll use the current page's headers for prefetch requests. 

If you do any cookie-based server-side tracking or analytics with Craft, that could wreck a little havoc. (Say your funnel is "load XXX page and then load the contact page." You'd be wondering why people visited the contact page but never filled it out.) 

If you use prerender, it looks like Chrome will actually execute any javascript on the page as well, which would also defeat any JS based analytics packages.) Scary.

(For what it's worth, I haven't tested any of these techniques at all but it would be interesting to see what kind of mainstream traction they receive. I can see for a web app it might be more useful.)