"The Chrome Security team has been a source of innovation in the browser security space. Tor Browser Bundle is based on Firefox and thus inherits progress made by Mozilla automatically. While improvements in Chrome may not be appropriate for Firefox, they could be integrated in Tor Browser Bundle. In a best case scenario, members of the Chrome Security team may be allowed to work with the Tor Project on these changes."
Basically it's saying: Chrome is also doing good stuff, combine it with the stuff you get from Mozilla for a better result.