Lots of folks note how Kernel 3.17 is supposed to fix trackpad issues. So, I initially installed 3.18 and found that my sound didn't work (? YMMV). Indeed, my trackpad did work, but my sound didn't. I then reinstalled elementary via elementaryos-chromebook and didn't update the kernel. Not updating the Kernel is reccommended:
http://shnatsel.blogspot.com/2013/12/why-you-should-not-upgrade-kernel-on.html
Here's what I did to get things working:
- Installed elementaryos-chromebook
- Booted into Elementary via Ctrl + L. Went through prompts.
- Went to Applications > Update Manager. Installed all updates.
- Installed Hardware updates first. Rebooted.