message: Don't assume we have a worker_thread_ on linux (for now)
  Tbr:
  No-Try: true
  Cr-Commit-Position: refs/heads/master@{#31019}
diff: @@ -769,6 +769,7 @@ void ReceiveStatisticsProxy::OnTimingFrameInfoUpdated(
  void ReceiveStatisticsProxy::RtcpPacketTypesCounterUpdated(
  uint32_t ssrc,
  const RtcpPacketTypeCounter& packet_counter) {
  +#if !defined(WEBRTC_LINUX)
  if (!worker_thread_->IsCurrent()) {
  // RtpRtcp::Configuration has a single RtcpPacketTypeCounterObserver and
  // that same configuration may be used for both receiver and sender
  @@ -791,6 +792,7 @@ void ReceiveStatisticsProxy::RtcpPacketTypesCounterUpdated(
  }
  RTC_DCHECK_RUN_ON(&main_thread_);
  +#endif
  rtc::CritScope lock(&crit_);
  if (stats_.ssrc != ssrc)
  return;
  