Yes, I also find it odd that it's not included in the Chromium version by default as it was by my understanding developed by the chromium guys, and should therefore be open source. They did this to work around all the problems with trying to launch either evince or adobes PDF reader. It might be an Adobe license issue, but I don't know.
I take a slightly different approach, and just have chromium and goggle chrome dev installed on my workstation, and just copy the libpdf.so from /opt/google/chrome to /use/lib/chromium-browser. I also copy over the other .so files which work and the new google apps in the resources dir.
It's good to see that a few of the main distros are looking to include stable versions of chromium in their repos, as I prefer the fully open source version to having to use the Google version, choice is good
. Here's hoping that this will always be possible and the two versions don't start to drift to far apart.