message: Fix CallPerfTests to call Call::GetStats() from the right thread.
  Cr-Commit-Position: refs/heads/master@{#28785}
diff: @@ -860,19 +860,22 @@ void CallPerfTest::TestMinAudioVideoBitrate(int test_bitrate_from,
  class MinVideoAndAudioBitrateTester : public test::EndToEndTest {
  public:
  - MinVideoAndAudioBitrateTester(int test_bitrate_from,
  + MinVideoAndAudioBitrateTester(
  + int test_bitrate_from,
  int test_bitrate_to,
  int test_bitrate_step,
  int min_bwe,
  int start_bwe,
  - int max_bwe)
  + int max_bwe,
  + test::SingleThreadedTaskQueueForTesting* task_queue)
  : EndToEndTest(),
  test_bitrate_from_(test_bitrate_from),
  test_bitrate_to_(test_bitrate_to),
  test_bitrate_step_(test_bitrate_step),
  min_bwe_(min_bwe),
  start_bwe_(start_bwe),
  - max_bwe_(max_bwe) {}
  + max_bwe_(max_bwe),
  + task_queue_(task_queue) {}
  protected:
  BuiltInNetworkBehaviorConfig GetFakeNetworkPipeConfig() {
  @@ -922,15 +925,17 @@ void CallPerfTest::TestMinAudioVideoBitrate(int test_bitrate_from,
  send_simulated_network_->SetConfig(pipe_config);
  receive_simulated_network_->SetConfig(pipe_config);
  - rtc::ThreadManager::Instance()->CurrentThread()->SleepMs(
  - quick_perf_test ? kShortDelayMs : kBitrateStabilizationMs);
  + rtc::Thread::SleepMs(quick_perf_test ? kShortDelayMs
  + : kBitrateStabilizationMs);
  int64_t avg_rtt = 0;
  for (int i = 0; i < kBitrateMeasurements; i++) {
  - Call::Stats call_stats = sender_call_->GetStats();
  + Call::Stats call_stats;
  + task_queue_->SendTask(
  + [this, &call_stats]() { call_stats = sender_call_->GetStats(); });
  avg_rtt += call_stats.rtt_ms;
  - rtc::ThreadManager::Instance()->CurrentThread()->SleepMs(
  - quick_perf_test ? kShortDelayMs : kBitrateMeasurementMs);
  + rtc::Thread::SleepMs(quick_perf_test ? kShortDelayMs
  + : kBitrateMeasurementMs);
  }
  avg_rtt = avg_rtt / kBitrateMeasurements;
  if (avg_rtt > kMinGoodRttMs) {
  @@ -976,8 +981,9 @@ void CallPerfTest::TestMinAudioVideoBitrate(int test_bitrate_from,
  SimulatedNetwork* send_simulated_network_;
  SimulatedNetwork* receive_simulated_network_;
  Call* sender_call_;
  + test::SingleThreadedTaskQueueForTesting* const task_queue_;
  } test(test_bitrate_from, test_bitrate_to, test_bitrate_step, min_bwe,
  - start_bwe, max_bwe);
  + start_bwe, max_bwe, &task_queue_);
  RunBaseTest(&test);
  }
  