message: Handle case of empty connection in pair change event
  Cr-Commit-Position: refs/heads/master@{#28850}
diff: @@ -1965,15 +1965,17 @@ void P2PTransportChannel::SwitchSelectedConnection(Connection* conn,
  }
  // Create event for candidate pair change.
  +
  + if (selected_connection_) {
  CandidatePairChangeEvent pair_change;
  pair_change.reason = reason;
  - if (selected_connection_) {
  pair_change.local_candidate = selected_connection_->local_candidate();
  pair_change.remote_candidate = selected_connection_->remote_candidate();
  pair_change.last_data_received_ms =
  selected_connection_->last_data_received();
  - }
  SignalCandidatePairChanged(pair_change);
  + }
  +
  SignalNetworkRouteChanged(network_route_);
  }
  