| // META: script=resources/utils.js |
| |
| async_test(t => { |
| assert_implements(window.PerformanceLongTaskTiming, 'Longtasks are not supported.'); |
| // Create a long task before any observer. |
| const begin = window.performance.now(); |
| while (window.performance.now() < begin + 60); |
| // After a timeout, add an observer with buffered flag. |
| t.step_timeout(() => { |
| new PerformanceObserver(t.step_func_done(list => { |
| list.getEntries().forEach(entry => { |
| checkLongTaskEntry(entry); |
| }); |
| })).observe({type: 'longtask', buffered: true}); |
| }, 0); |
| }, 'PerformanceObserver with buffered flag can see previous longtask entries.'); |