Add fraction loss in visualization tool.

Review-Url: https://codereview.webrtc.org/2204713005
Cr-Commit-Position: refs/heads/master@{#13644}
diff --git a/webrtc/tools/event_log_visualizer/analyzer.h b/webrtc/tools/event_log_visualizer/analyzer.h
index 2853e86..dc56c5f 100644
--- a/webrtc/tools/event_log_visualizer/analyzer.h
+++ b/webrtc/tools/event_log_visualizer/analyzer.h
@@ -41,6 +41,8 @@
 
   void CreateAccumulatedDelayChangeGraph(Plot* plot);
 
+  void CreateFractionLossGraph(Plot* plot);
+
   void CreateTotalBitrateGraph(PacketDirection desired_direction, Plot* plot);
 
   void CreateStreamBitrateGraph(PacketDirection desired_direction, Plot* plot);