Add default constructor for rtc::Event

Bug: webrtc:9962
Change-Id: Icaa91e657e6881fcb1553f354c07866109a0ea68
Reviewed-on: https://webrtc-review.googlesource.com/c/109500
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25535}
diff --git a/rtc_base/event_tracer.cc b/rtc_base/event_tracer.cc
index 201abdd..af88c9d 100644
--- a/rtc_base/event_tracer.cc
+++ b/rtc_base/event_tracer.cc
@@ -90,8 +90,7 @@
       : logging_thread_(EventTracingThreadFunc,
                         this,
                         "EventTracingThread",
-                        kLowPriority),
-        shutdown_event_(false, false) {}
+                        kLowPriority) {}
   ~EventLogger() { RTC_DCHECK(thread_checker_.CalledOnValidThread()); }
 
   void AddTraceEvent(const char* name,