The TotalFinder project's recent release includes Chrome-style tabs, taken directly from the Chrome tree. I think this is the first project I've heard of that isn't directly browser related that has used code from Chrome.
Here's the relevant section of that page, just in case it changes in the future:
I had an idea of bringing tabs experience into Finder back in November 2009. Obviously this is a hard task, but so exciting. I’m quite new to Cocoa and I’ve never implemented such a complex UI element in Cocoa before. But I’m not afraid to search the internet and get deep into problems I happen to be exploring.
Luckily enough, there is a great state-of-the-art open source tabs implementation in the Chromium project available. I’ve studied briefly their codebase and it looked as a promising path to follow. I took their main browser window implementation and also components realizing tabs and extracted them from the main project. I’ve spent few days stripping dependencies and isolating functionality I needed. Dirty job but it paid off. After few evenings I’ve got working skeleton app with blank tabs.
I’d like to thank Google to made this all possible. I was really surprised how clean and well-documented the Chrome code is. People working on it earned my full respect. Kudos guys!