In the ebuild: RDEPEND=">=x11-base/xorg-server-1.9" DEPEND=" ${RDEPEND} x11-libs/libX11 x11-libs/libXext x11-libs/libXv x11-libs/libXvMC x11-libs/libdrm " The build-time dependencies are actually run-time dependencies for /usr/lib/libchromeXvMC*.so*. I suggest adding a USE=xvmc flag, moving the dependencies above to "xvmc?" in RDEPEND, and installing libchromeXvMC*.so* only when USE=xvmc is enabled.
Ping?
There's no config option to disable xvmc. Please work with upstream to add it.