Make RtcEventLogImpl to use a TaskQueue instead of a helper-thread

webrtc/logging/BUILD.gn

Index: webrtc/logging/BUILD.gn
diff --git a/webrtc/logging/BUILD.gn b/webrtc/logging/BUILD.gn
index 6b1e549d3031a4eef4a90eca361b2895010f8dbe..fac7e3d9b451364a40718fbf625d1b1bceda7674 100644
--- a/webrtc/logging/BUILD.gn
+++ b/webrtc/logging/BUILD.gn
@@ -40,8 +40,6 @@ rtc_static_library("rtc_event_log_impl") {
     "rtc_event_log/rtc_event_log.cc",
     "rtc_event_log/rtc_event_log_factory.cc",
     "rtc_event_log/rtc_event_log_factory.h",
-    "rtc_event_log/rtc_event_log_helper_thread.cc",
-    "rtc_event_log/rtc_event_log_helper_thread.h",
   ]
 
   defines = []
@@ -54,6 +52,8 @@ rtc_static_library("rtc_event_log_impl") {
     "../modules/rtp_rtcp",
     "../rtc_base:protobuf_utils",
     "../rtc_base:rtc_base_approved",
+    "../rtc_base:rtc_task_queue",
+    "../rtc_base:sequenced_task_checker",
     "../system_wrappers",
   ]