Add a chart for packet loss on incoming streams.

Also add stream names to labels.

R=philipel@webrtc.org

Review URL: https://codereview.webrtc.org/2317113003 .

Cr-Commit-Position: refs/heads/master@{#14159}
diff --git a/webrtc/tools/event_log_visualizer/analyzer.h b/webrtc/tools/event_log_visualizer/analyzer.h
index 74c0ff0..402f75f 100644
--- a/webrtc/tools/event_log_visualizer/analyzer.h
+++ b/webrtc/tools/event_log_visualizer/analyzer.h
@@ -68,6 +68,8 @@
 
   void CreateSequenceNumberGraph(Plot* plot);
 
+  void CreateIncomingPacketLossGraph(Plot* plot);
+
   void CreateDelayChangeGraph(Plot* plot);
 
   void CreateAccumulatedDelayChangeGraph(Plot* plot);
@@ -110,11 +112,13 @@
       const std::map<StreamId, std::vector<T>>& packets,
       const std::string& label_prefix);
 
-  bool IsRtxSsrc(StreamId stream_id);
+  bool IsRtxSsrc(StreamId stream_id) const;
 
-  bool IsVideoSsrc(StreamId stream_id);
+  bool IsVideoSsrc(StreamId stream_id) const;
 
-  bool IsAudioSsrc(StreamId stream_id);
+  bool IsAudioSsrc(StreamId stream_id) const;
+
+  std::string GetStreamName(StreamId) const;
 
   const ParsedRtcEventLog& parsed_log_;