Chrubuntu on Acer C7 is really cool, except for one flaw - the touchpad is not responsive when it is not plugged on. The issue is that the Synaptics driver default settings for sensitivity is set too low. We have to make it more sensitive. It is weird though that the trackpad works perfectly if the laptop is plugged.

Edit 1: Added fix for pointer moving when you click the touchpad. The touchpad registers two events, small pointer movement and the actual click.

Step 1: Adjust Some Synaptics Options

Make synaptics adjustments by running

# If you feel the trackpad is still not sensitive enough, you can try values 10/5 instead of 20/10
synclient fingerhigh=20
synclient fingerlow=10

# These values control how much movement the touchpad must detect before moving the pointer.
# Using right hand for moving, left hand to click, and keeping the right hand on the touchpad helps.
# If the pointer still moves a lot, bump this to "24" value.
synclient HorizHysteresis=12
synclient VertHysteresis=12

Step 2: Make Changes Permanent

Edit /usr/share/X11/xorg.conf.d/50-synaptics.conf by running:

      sudo gedit /usr/share/X11/xorg.conf.d/50-synaptics.conf

Find the line

       MatchDevicePath "/dev/input/event*"

and add these after

      Option "FingerHigh"    "10"
      Option "FingerLow"     "5"
Option   "HorizHysteresis" "12"
Option   "VertHysteresis" "12"