Fetch traces from the wild.
The demo here contains a box with a slow click handler, a button to fetch resources, and a button to download a trace, containing the information recorded by a PerformanceObserver.
Here's a sample trace.
Include this script in the page early enough for the PerformanceObserver to observe all target entries. The following globals are exposed.
Downloads the generated .trace.json file to disk. This trace can be loaded into chrome://tracing/.
Returns a string that can be saved to a .trace.json file.
Returns an array of the synthesized trace event objects.