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/modules/utility/source/process_thread_impl.cc b/modules/utility/source/process_thread_impl.cc
index 73338ac..20f26d9 100644
--- a/modules/utility/source/process_thread_impl.cc
+++ b/modules/utility/source/process_thread_impl.cc
@@ -44,9 +44,7 @@
 }
 
 ProcessThreadImpl::ProcessThreadImpl(const char* thread_name)
-    : wake_up_(/*manual_reset=*/false, /*initially_signaled=*/false),
-      stop_(false),
-      thread_name_(thread_name) {}
+    : stop_(false), thread_name_(thread_name) {}
 
 ProcessThreadImpl::~ProcessThreadImpl() {
   RTC_DCHECK(thread_checker_.CalledOnValidThread());