Using performance.mark() with Chrome dev tools performance tab

In the new performance tab markers show up in “User Timing”.
You need to use

performance.measure()

to mark the start and end of your marks
like this:

performance.mark('myMark-start');

// your code 

performance.mark('myMark-end');
performance.measure('myPerfMarker', 'myMark-start', 'myMark-end');