Comment 9 for bug 1308264

Found a solution to this that works at least for Acer Chromebook c720. Basically you need to change your kernel as is hinted above and then fix the trackpad.

1) Download and install another kernel. I used 3.14.4 (http://kernel.ubuntu.com/~kernel-ppa/mainline/v3.14.4-utopic/). You'll need to grab 3 files: the headers _all, header-generic, and image-generic. Install the packages in that order.

2) Reboot, open up terminal and run "uname -r" (without quotes) and make sure you've booted into kernel 3.14.4

3) While in terminal, download the cros-haswell-modules script (this is part of chrubuntu):
wget http://goo.gl/kz917j

4) Open up the script for editing:
sudo gedit kz917j

5) Locate the following lines:
# Grab Ubuntu kernel source
apt-get source linux-image-$mykern
cd $mykernver

Change this section to the following:
# Grab Ubuntu kernel source
#apt-get source linux-image-$mykern
#cd $mykernver
wget http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.14.4.tar.xz
tar -xJf linux-3.14.4.tar.xz
cd linux-3.14.4

NOTE: Replace "3.14.4" with whatever kernel version you are using if you downloaded something different in step 1

6) Save the changes and close gedit. Back in terminal, type:
bash kz917j

Let the script run. If you encounter a message that says something along the lines of the patch already being applied, just type "y" and hit enter, and the script will continue executing. I think I may have had to do that a few times while the script executed.

7) After the script is done, just reboot and you should be good to go! Running 14.04 LTS, kernel 3.14.4 on an Acer c720 here and it boots up in ~15 seconds. Everything is working fine as far as I can tell!