This is what i was looking for, but sadly wasn’t available till now :
Came across it while looking thru the Google IO videos : http://www.youtube.com/watch?v=2OgAetgR_ok
Time : 3.25.
Looks straightforward…will try it out soon and update here….
Other Tools (mentioned in the video) :
responsive inspector extension
Basically see : cloud based testing
And Automated Testing : http://goo.gl/5WsMy
Google Analytics Live Feed….for ur app upto the level of Device Breakpoints and Page Load Speeds.