Tests user timing events in traces.
Recording started
Tracing complete

Below offsets and startTimes are rounded to avoid flakiness on the bots.
FYI: startTime in args is the equivalent DOMHighResTimeStamp.

Marks:
ph name                offset from ~zero   args
I  ~zero                            0 ms   {"data":{"callTime":0,"navigationId":"xNavIdx","sampleTraceId":0,"startTime":0}}
I  @500                           500 ms   {"data":{"callTime":0,"navigationId":"xNavIdx","sampleTraceId":0,"startTime":500}}
I  @1000                         1000 ms   {"data":{"callTime":0,"navigationId":"xNavIdx","sampleTraceId":0,"startTime":1000}}
I  @1200                         1200 ms   {"data":{"callTime":0,"navigationId":"xNavIdx","sampleTraceId":0,"startTime":1200}}
I  @1500                         1500 ms   {"data":{"callTime":0,"detail":"{\"aProperty\":\"This is a property\"}","navigationId":"xNavIdx","sampleTraceId":0,"startTime":1500}}

Measures:
ph name                offset from ~zero   args
b  ~zero to @500                    0 ms   {"callTime":0,"startTime":0,"traceId":0}
e  ~zero to @500                  500 ms   {}
b  @1000 to @1200                1000 ms   {"callTime":0,"detail":"\"its @1000 to @1200\"","startTime":1000,"traceId":0}
e  @1000 to @1200                1200 ms   {}
b  @1500 for 200                 1500 ms   {"callTime":0,"detail":"{\"key\":\"val\",\"num\":123}","startTime":1500,"traceId":0}
e  @1500 for 200                 1700 ms   {}
b  @2000 for 300                 2000 ms   {"callTime":0,"startTime":2000,"traceId":0}
e  @2000 for 300                 2300 ms   {}