Define a protobuf format for representing plots. Add code to convert the C-representation generated by the RtcEventLog analysis tool, to the new protobuf format.

BUG=webrtc:6249

NOTRY=True

Review-Url: https://codereview.webrtc.org/2268063002
Cr-Commit-Position: refs/heads/master@{#13873}
diff --git a/webrtc/tools/event_log_visualizer/plot_protobuf.cc b/webrtc/tools/event_log_visualizer/plot_protobuf.cc
new file mode 100644
index 0000000..7f032c1
--- /dev/null
+++ b/webrtc/tools/event_log_visualizer/plot_protobuf.cc
@@ -0,0 +1,81 @@
+/*
+ *  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.
+ */
+
+#include "webrtc/tools/event_log_visualizer/plot_protobuf.h"
+
+#include <memory>
+
+namespace webrtc {
+namespace plotting {
+
+ProtobufPlot::ProtobufPlot() {}
+
+ProtobufPlot::~ProtobufPlot() {}
+
+void ProtobufPlot::Draw() {}
+
+void ProtobufPlot::ExportProtobuf(protobuf_plot::Plot* plot) {
+  for (size_t i = 0; i < series_list_.size(); i++) {
+    protobuf_plot::DataSet* data_set = plot->add_data_sets();
+    for (const auto& point : series_list_[i].points) {
+      data_set->add_xvalues(point.x);
+    }
+    for (const auto& point : series_list_[i].points) {
+      data_set->add_yvalues(point.y);
+    }
+
+    if (series_list_[i].style == BAR_GRAPH) {
+      data_set->set_style(protobuf_plot::BAR_GRAPH);
+    } else if (series_list_[i].style == LINE_GRAPH) {
+      data_set->set_style(protobuf_plot::LINE_GRAPH);
+    } else if (series_list_[i].style == LINE_DOT_GRAPH) {
+      data_set->set_style(protobuf_plot::LINE_DOT_GRAPH);
+    } else {
+      data_set->set_style(protobuf_plot::UNDEFINED);
+    }
+
+    data_set->set_label(series_list_[i].label);
+  }
+
+  plot->set_xaxis_min(xaxis_min_);
+  plot->set_xaxis_max(xaxis_max_);
+  plot->set_yaxis_min(yaxis_min_);
+  plot->set_yaxis_max(yaxis_max_);
+  plot->set_xaxis_label(xaxis_label_);
+  plot->set_yaxis_label(yaxis_label_);
+  plot->set_title(title_);
+}
+
+ProtobufPlotCollection::ProtobufPlotCollection() {}
+
+ProtobufPlotCollection::~ProtobufPlotCollection() {}
+
+void ProtobufPlotCollection::Draw() {}
+
+void ProtobufPlotCollection::ExportProtobuf(
+    protobuf_plot::PlotCollection* collection) {
+  for (const auto& plot : plots_) {
+    // TODO(terelius): Ensure that there is no way to insert plots other than
+    // ProtobufPlots in a ProtobufPlotCollection. Needed to safely static_cast
+    // here.
+    protobuf_plot::Plot* protobuf_representation = collection->add_plots();
+    static_cast<ProtobufPlot*>(plot.get())
+        ->ExportProtobuf(protobuf_representation);
+  }
+}
+
+Plot* ProtobufPlotCollection::AppendNewPlot() {
+  Plot* plot = new ProtobufPlot();
+  plots_.push_back(std::unique_ptr<Plot>(plot));
+  return plot;
+}
+
+}  // namespace plotting
+}  // namespace webrtc