Aligning time in audio jitter buffer plot to other plots in rtc event log visualizer.

Bug: webrtc:9147
Change-Id: I4ddb3e93ea04a11a68e097ecad731d6d9d6842a9
Reviewed-on: https://webrtc-review.googlesource.com/75322
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Reviewed-by: Henrik Lundin <henrik.lundin@webrtc.org>
Commit-Queue: Minyue Li <minyue@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#23712}

rtc_tools/event_log_visualizer/main.cc

@@ -335,8 +335,12 @@ int main(int argc, char* argv[]) {
           "audio_processing/conversational_speech/EN_script2_F_sp2_B1", "wav");
     }
     auto neteq_stats = analyzer.SimulateNetEq(wav_path, 48000);
-    analyzer.CreateAudioJitterBufferGraph(neteq_stats,
-                                          collection->AppendNewPlot());
+
+    if (!neteq_stats.empty()) {
+      analyzer.CreateAudioJitterBufferGraph(neteq_stats,
+                                            collection->AppendNewPlot());
+    }
+
     analyzer.CreateNetEqStatsGraph(
         neteq_stats,
         [](const webrtc::NetEqNetworkStatistics& stats) {