Using and android phone as a usb shield for arduino board. Control over WIFI/3G

Hey guys!

I am building an internet controlled robot using an android phone as a shield connecting via USB to the arduino UNO
I am using another android device (Tablet) to connect the phone via WIFI/3G which controls Arduino.
So the scheme of connection should be like this

Tablet->android phone->usb->Arduino UNO

I found 2 apps on Google Play
Droid control for arduino https://play.google.com/store/apps/details?id=arduino.robot.control
Droid host for arduino https://play.google.com/store/apps/details?id=arduino.robot

Example video from the App developer PRESS ME

1st one is installed on the tablet and the 2nd one is on the phone that is connected to the arduino

So I have a question concerning the sketch for the arduino. What should be the source code for the board? I mailed and commented to the guy who created the apps but there was no response from him.

I am quite new in arduino so I would appreciate if you guys helped me with that.