with Window Resize code example

Example 1: js window resize listener

//listen for window resize event
window.addEventListener('resize', function(event){
    var newWidth = window.innerWidth;
    var newHeight = window.innerHeight; 
});

Example 2: resize browser window

To resize browser window 
-I would create object of dimensions class
Dimension newD = new Dimension(480,620)
-Than I resize the current window to the given dimension
driver.manage().window().setSize(newD)