Adding a custom resolution on Ubuntu 12.04 for my Chromebook Pixel

Quick note about how I managed to solve this.

Commands are in RED:

First you get the info you'll need for the next command using cvt and the resolution:

user@Machine:~$ cvt 1680 1120
# 1680x1120 59.89 Hz (CVT) hsync: 69.59 kHz; pclk: 157.00 MHz
Modeline "1680x1120_60.00"  157.00  1680 1792 1968 2256  1120 1123 1133 1162 -hsync +vsync

Then you run the xrandr with the information in bold returned by the previous command:

user@Machine:~$ sudo xrandr --newmode "1680x1120_60.00"  157.00  1680 1792 1968 2256  1120 1123 1133 1162 -hsync +vsync

Now you find out the name of the display being used with xrandr -q:

user@Machine:~$ sudo xrandr -q
Screen 0: minimum 320 x 200, current 1600 x 1024, maximum 8192 x 8192
eDP1 connected 1600x1024+0+0 (normal left inverted right x axis y axis) 272mm x 181mm
   2560x1700      60.0 +
   2048x1536      60.0 
   1920x1440      60.0 
   1856x1392      60.0 
   1792x1344      60.0 
   1920x1200      60.0 
   1920x1080      59.9 
   1600x1200      60.0 
   1680x1050      60.0     59.9 
   1600x1024      60.2*
   1400x1050      60.0 
   1280x1024      60.0 
   1440x900       59.9 
   1280x960       60.0 
   1360x768       59.8     60.0 
   1152x864       60.0 
   1024x768       60.0 
   800x600        60.3     56.2 
   640x480        59.9 
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
  1680x1120_60.00 (0x124)  157.0MHz
        h: width  1680 start 1792 end 1968 total 2256 skew    0 clock   69.6KHz
        v: height 1120 start 1123 end 1133 total 1162           clock   59.9Hz

And now you'll add your new resolution using guess who? Yes... xrand.

user@Machine:~$ sudo xrandr --addmode eDP1 1680x1120_60.00

That's it... quick and painless...