OnKeyDown in Android PageRenderer

Can I use OnKeyDown to capture back button events in an native Android PageRenderer.

public override bool OnKeyDown (Keycode keyCode, KeyEvent e)

{          
        if (keyCode == Keycode.Back) 
        {
      
                return false;
        
}
 
        return true;
}


This is to capture back clicks when displaying a WebView.

Point 9 here states that this should be possible using a standard Android activity.

thanks