How can I fix the touchpad on my Chromebook 14 using Ubuntu 14.04?

Good news! The latest version of the Linux Kernel now supports chromebook natively and officially. No patching required.

If you are running a version before 3.17 then you need to update. Check your version.

uname -r

To update manually, run the following (64-bit, 14.10 only):

cd /tmp
sudo mkdir kernel
cd kernel
sudo wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.17-rc1-utopic/linux-headers-3.17.0-031700rc1-generic_3.17.0-031700rc1.201409021903_amd64.deb
sudo wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.17-rc1-utopic/linux-headers-3.17.0-031700rc1_3.17.0-031700rc1.201409021903_all.deb
sudo wget http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.17-rc1-utopic/linux-image-3.17.0-031700rc1-generic_3.17.0-031700rc1.201409021903_amd64.deb
sudo dpkg -i *.deb
sudo reboot 

Give the boot process at least 5 minutes to finish the first time, ignore the string error you will get

Source: http://www.reddit.com/r/chrubuntu/comments/1rsxkd/list_of_fixes_for_xubuntu_1310_on_the_acer_c720/