I know this questions has been asked a few times here. But these seem fairly outdated, and it looks like the Adsense for Ajax project has been canned (or at the very least,
The best solution to this problem is to provide static alternative pages. If you're pushing history state then you must have already come up with a URI scheme to describe "pages" on your site. Now all you have to do is serve static copies of those pages to browsers without javascript. In addition to letting the adsense bot see your content, this will also be good for SEO because it will allow the google web crawler to see your content.