Add NetEq delay plotting to event_log_visualizer

This CL adds the capability to analyze and plot how NetEq behaves in
response to a network trace.

BUG=webrtc:7467

Review-Url: https://codereview.webrtc.org/2876423002
Cr-Commit-Position: refs/heads/master@{#18590}
diff --git a/webrtc/tools/event_log_visualizer/analyzer.h b/webrtc/tools/event_log_visualizer/analyzer.h
index 988f2cb..fab52b9 100644
--- a/webrtc/tools/event_log_visualizer/analyzer.h
+++ b/webrtc/tools/event_log_visualizer/analyzer.h
@@ -100,6 +100,9 @@
   void CreateAudioEncoderEnableFecGraph(Plot* plot);
   void CreateAudioEncoderEnableDtxGraph(Plot* plot);
   void CreateAudioEncoderNumChannelsGraph(Plot* plot);
+  void CreateAudioJitterBufferGraph(const std::string& replacement_file_name,
+                                    int file_sample_rate_hz,
+                                    Plot* plot);
 
   // Returns a vector of capture and arrival timestamps for the video frames
   // of the stream with the most number of frames.
@@ -163,6 +166,13 @@
 
   std::map<StreamId, std::vector<LoggedRtcpPacket>> rtcp_packets_;
 
+  // Maps an SSRC to the timestamps of parsed audio playout events.
+  std::map<uint32_t, std::vector<uint64_t>> audio_playout_events_;
+
+  // Stores the timestamps for all log segments, in the form of associated start
+  // and end events.
+  std::vector<std::pair<uint64_t, uint64_t>> log_segments_;
+
   // A list of all updates from the send-side loss-based bandwidth estimator.
   std::vector<LossBasedBweUpdate> bwe_loss_updates_;