As far as I can see gfx::ColorSpace supports old-style IPC (ui/gfx/ipc/color/gfx_param_traits.h), but doesn't support Mojo IPC yet (since I don't see any mentions of colorspace under ui/gfx/mojo.
Since we are using Mojo in Chromecast and we pass media::VideoDecoderConfig via Mojo, and since gfx::ColorSpace is now part of the VideoDecoderConfig, we'll need to add support to mojo IPC for the gfx::ColorSpace type.