Add new step graph type to event log visualization tool

webrtc/tools/event_log_visualizer/plot_base.h

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 #ifndef WEBRTC_TOOLS_EVENT_LOG_VISUALIZER_PLOT_BASE_H_
 #define WEBRTC_TOOLS_EVENT_LOG_VISUALIZER_PLOT_BASE_H_
 
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 namespace webrtc {
 namespace plotting {
 
-enum PlotStyle { LINE_GRAPH, LINE_DOT_GRAPH, BAR_GRAPH };
+enum PlotStyle { LINE_GRAPH, LINE_DOT_GRAPH, BAR_GRAPH, LINE_STEP_GRAPH };
 
 struct TimeSeriesPoint {
   TimeSeriesPoint(float x, float y) : x(x), y(y) {}
   float x;
   float y;
 };
 
 struct TimeSeries {
   TimeSeries() = default;
   TimeSeries(TimeSeries&& other)
@@ skipping 84 matching lines @@
   virtual Plot* AppendNewPlot() = 0;
 
  protected:
   std::vector<std::unique_ptr<Plot> > plots_;
 };
 
 }  // namespace plotting
 }  // namespace webrtc
 
 #endif  // WEBRTC_TOOLS_EVENT_LOG_VISUALIZER_PLOT_BASE_H_