Hiding softkeys of Android devices.

Hi friends,
I want to play my game in full screen mode on nexus device and I don’t know how can I hide those softkeys in my unity game. Please can anybody tell me how do I achieve this.

This is called immersive fullscreen mode: Hide system bars for immersive mode  |  Android Developers
It will be supported in Unity 5. For now, you could use a plugin from asset store, or write your own plugin.