Trace where timers were scheduled in Blink

Source/core/html/MediaController.cpp

 /*
  * Copyright (C) 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 135 matching lines @@
 }
 
 double MediaController::currentTime() const
 {
     if (m_mediaElements.isEmpty())
         return 0;
 
     if (m_position == MediaPlayer::invalidTime()) {
         // Some clocks may return times outside the range of [0..duration].
         m_position = max(0.0, min(duration(), m_clock->currentTime()));
-        m_clearPositionTimer.startOneShot(0);
+        m_clearPositionTimer.startOneShot(0, FROM_HERE);
     }
 
     return m_position;
 }
 
 void MediaController::setCurrentTime(double time, ExceptionState& exceptionState)
 {
     // When the user agent is to seek the media controller to a particular new playback position,
     // it must follow these steps:
     // If the new playback position is less than zero, then set it to zero.
@@ skipping 365 matching lines @@
         if (!m_mediaElements[index]->ended())
             allHaveEnded = false;
     }
     return allHaveEnded;
 }
 
 void MediaController::scheduleEvent(const AtomicString& eventName)
 {
     m_pendingEvents.append(Event::createCancelable(eventName));
     if (!m_asyncEventTimer.isActive())
-        m_asyncEventTimer.startOneShot(0);
+        m_asyncEventTimer.startOneShot(0, FROM_HERE);
 }
 
 void MediaController::asyncEventTimerFired(Timer<MediaController>*)
 {
     Vector<RefPtr<Event> > pendingEvents;
 
     m_pendingEvents.swap(pendingEvents);
     size_t count = pendingEvents.size();
     for (size_t index = 0; index < count; ++index)
         dispatchEvent(pendingEvents[index].release(), IGNORE_EXCEPTION);
@@ skipping 73 matching lines @@
 
 // The spec says to fire periodic timeupdate events (those sent while playing) every
 // "15 to 250ms", we choose the slowest frequency
 static const double maxTimeupdateEventFrequency = 0.25;
 
 void MediaController::startTimeupdateTimer()
 {
     if (m_timeupdateTimer.isActive())
         return;
 
-    m_timeupdateTimer.startRepeating(maxTimeupdateEventFrequency);
+    m_timeupdateTimer.startRepeating(maxTimeupdateEventFrequency, FROM_HERE);
 }
 
 void MediaController::timeupdateTimerFired(Timer<MediaController>*)
 {
     scheduleTimeupdateEvent();
 }
 
 void MediaController::scheduleTimeupdateEvent()
 {
     double now = WTF::currentTime();
     double timedelta = now - m_previousTimeupdateTime;
 
     if (timedelta < maxTimeupdateEventFrequency)
         return;
 
     scheduleEvent(EventTypeNames::timeupdate);
     m_previousTimeupdateTime = now;
 }