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

webrtc/pc/peerconnection.cc

 /*
  *  Copyright 2012 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.
  */
 
@@ skipping 1319 matching lines @@
   // Update stats here so that we have the most recent stats for tracks and
   // streams before the channels are closed.
   stats_->UpdateStats(kStatsOutputLevelStandard);
 
   session_->Close();
   network_thread()->Invoke<void>(
       RTC_FROM_HERE,
       rtc::Bind(&cricket::PortAllocator::DiscardCandidatePool,
                 port_allocator_.get()));
 
-  factory_->worker_thread()->Invoke<void>(RTC_FROM_HERE,
-                                          [this] { call_.reset(); });
-
-  // The event log must outlive call (and any other object that uses it).
-  event_log_.reset();
+  factory_->worker_thread()->Invoke<void>(RTC_FROM_HERE, [this] {
+    call_.reset();
+    // The event log must outlive call (and any other object that uses it).
+    event_log_.reset();
+  });
 }
 
 void PeerConnection::OnSessionStateChange(WebRtcSession* /*session*/,
                                           WebRtcSession::State state) {
   switch (state) {
     case WebRtcSession::STATE_INIT:
       ChangeSignalingState(PeerConnectionInterface::kStable);
       break;
     case WebRtcSession::STATE_SENTOFFER:
       ChangeSignalingState(PeerConnectionInterface::kHaveLocalOffer);
@@ skipping 1169 matching lines @@
   return event_log_->StartLogging(file, max_size_bytes);
 }
 
 void PeerConnection::StopRtcEventLog_w() {
   if (event_log_) {
     event_log_->StopLogging();
   }
 }
 
 }  // namespace webrtc