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

webrtc/logging/BUILD.gn

 # Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("../webrtc.gni")
 import("//third_party/protobuf/proto_library.gni")
@@ skipping 21 matching lines @@
     "../call:video_stream_api",
     "../rtc_base:rtc_base_approved",
   ]
 }
 
 rtc_static_library("rtc_event_log_impl") {
   sources = [
     "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 = []
 
   deps = [
     ":rtc_event_log_api",
     "..:webrtc_common",
     "../modules/audio_coding:audio_network_adaptor",
     "../modules/remote_bitrate_estimator:remote_bitrate_estimator",
     "../modules/rtp_rtcp",
@@ skipping 132 matching lines @@
         "../rtc_base:rtc_base_approved",
         "//third_party/gflags",
       ]
       if (!build_with_chromium && is_clang) {
         # Suppress warnings from the Chromium Clang plugin (bugs.webrtc.org/163).
         suppressed_configs += [ "//build/config/clang:find_bad_constructs" ]
       }
     }
   }
 }