Add new step graph type to event log visualization tool

webrtc/tools/event_log_visualizer/plot_protobuf.cc

Index: webrtc/tools/event_log_visualizer/plot_protobuf.cc
diff --git a/webrtc/tools/event_log_visualizer/plot_protobuf.cc b/webrtc/tools/event_log_visualizer/plot_protobuf.cc
index e6e1adc703313c50b8e3dd4380fb3aaee3fc610c..6e4558579bcd4343ce08cc0e58e79c850e6f199b 100644
--- a/webrtc/tools/event_log_visualizer/plot_protobuf.cc
+++ b/webrtc/tools/event_log_visualizer/plot_protobuf.cc
@@ -38,6 +38,8 @@ void ProtobufPlot::ExportProtobuf(webrtc::analytics::Chart* chart) {
     } else if (series_list_[i].style == LINE_DOT_GRAPH) {
       data_set->set_style(webrtc::analytics::ChartStyle::LINE_CHART);
       data_set->set_highlight_points(true);
+    } else if (series_list_[i].style == LINE_STEP_GRAPH) {
+      data_set->set_style(webrtc::analytics::ChartStyle::LINE_STEP_CHART);
     } else {
       data_set->set_style(webrtc::analytics::ChartStyle::UNDEFINED);
     }