Well here is the answer.

“One overriding goal we have had from the start has been to build the best browser we can. When it comes to Mac and Linux versions, this means that our goal is not to just “port” a Windows application to these other platforms–rather, our goal is to deliver Chromium’s innovative, Google-style user interface without rough edges on any of them. – In order to make sure Chromium feels right, each platform’s version is being built by people who live and breathe that platform; the engineers working on these versions are long-time Mac and Linux engineers who are just as picky about the details as anyone”

You can read the whole story here: Platforms and Priorities