[HTMLMediaElement] Reschedule timeupdate event if fired too early

https://bugs.webkit.org/show_bug.cgi?id=279055

Reviewed by Xabier Rodriguez-Calvar.

HTMLMediaElement fires 'timeupdate' every 250ms in repeating timer. If the
timer is fired before 250ms from the last occurrence, it is silently skipped
and needs to wait for another 250ms. As a result, the gap between two
following timeupdate events may vary 250-500ms.

This may happen in two cases:

1) Non-periodic timeupdate event is scheduled for any reason.
2) When the difference between two timer calls is lower than 250ms. This may
happen when there are multiple timers to handle at the same time in
ThreadTimers (maxDurationOfFiringTimers).

Original author: Andrzej Surdej <Andrzej_Surdej@comcast.com>

See: #1392

* Source/WebCore/html/HTMLMediaElement.cpp:
(WebCore::HTMLMediaElement::scheduleTimeupdateEvent): Schedule next event on the remaining time difference so that maxTimeupdateEventFrequency is honored, instead of waiting a full cycle.

Canonical link: https://commits.webkit.org/283264@main

Author: asurdej-comcast

Source/WebCore/html/HTMLMediaElement.cpp

@@ -4248,8 +4248,11 @@ void HTMLMediaElement::scheduleTimeupdateEvent(bool periodicEvent)
     Seconds timedelta = now - m_clockTimeAtLastUpdateEvent;
 
     // throttle the periodic events
-    if (periodicEvent && timedelta < maxTimeupdateEventFrequency)
+    if (periodicEvent && timedelta < maxTimeupdateEventFrequency) {
+        // Reschedule the timer to fire at the correct time, ensuring that no full cycles are skipped
+        m_playbackProgressTimer.start(maxTimeupdateEventFrequency - timedelta, maxTimeupdateEventFrequency);
         return;
+    }
 
     // Some media engines make multiple "time changed" callbacks at the same time, but we only want one
     // event at a given time so filter here