Changing css media type in browser

Is there some means of specifying the default media type for a browser (let's say chrome), so that I can test css @media styles?

@screen   
{  
    div { background-color:red; }  
}  

@handheld  
{  
     div { background-color:lime; }  
}

<div style="width:100px;height:100px"></div>

Such that I could (without touching my code) test the two media types in the browser? Changing the media type would change the color of the div above. A chrome extension, a bit of javascript or some other magic would be greatly appreciated.