You're right - although many of the building blocks are there, it appears there is no way to specify a colorspace or print profile when asking Chrome to emit a PDF (and I doubt the other browsers are any better). Skia (the PDF rendering engine that Chromium uses) actually supports colorspace transforms, but Chromium doesn't seem to hook that up to CSS or even support non-RGBA colors in its rendering pipeline.
You're right - although many of the building blocks are there, it appears there is no way to specify a colorspace or print profile when asking Chrome to emit a PDF (and I doubt the other browsers are any better). Skia (the PDF rendering engine that Chromium uses) actually supports colorspace transforms, but Chromium doesn't seem to hook that up to CSS or even support non-RGBA colors in its rendering pipeline.