Fix delay plot crash in event_log_visualizer.

NOTRY=true
BUG=webrtc:6510

Review-Url: https://codereview.webrtc.org/2410433002
Cr-Commit-Position: refs/heads/master@{#14588}

webrtc/tools/event_log_visualizer/analyzer.cc

@@ -1104,6 +1104,7 @@ void EventLogAnalyzer::CreateNetworkDelayFeedbackGraph(Plot* plot) {
   SimulatedClock clock(0);
   NullBitrateController null_controller;
   TransportFeedbackAdapter feedback_adapter(&clock, &null_controller);
+  feedback_adapter.InitBwe();
 
   TimeSeries time_series;
   time_series.label = "Network Delay Change";