For about two weeks I use the (still hard-masked) =www-client/chromium-15.0.8* series ebuilds which all compile fine under my AMD64 system using =sys-devel/gcc-4.6.1-r1. So I question me why the chromium-15.0.8* ebuilds are still hard-masked?
Please do not CC arches on your own.
Please see the faq section on chromium project page[1]. chromium-15* is currently the "dev channel". Although the dev channel releases may work fine for you, there are many variables involved, and they simply have not been tested as much as the stable or beta channel releases. [1] http://www.gentoo.org/proj/en/desktop/chromium/index.xml#doc_chap7_sect2