Add support for field trials to event log visualizer.

webrtc/tools/event_log_visualizer/main.cc

 /*
  *  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 <iostream>
 
 #include "gflags/gflags.h"
 #include "webrtc/logging/rtc_event_log/rtc_event_log_parser.h"
+#include "webrtc/test/field_trial.h"
 #include "webrtc/tools/event_log_visualizer/analyzer.h"
 #include "webrtc/tools/event_log_visualizer/plot_base.h"
 #include "webrtc/tools/event_log_visualizer/plot_python.h"
 
 DEFINE_bool(incoming, true, "Plot statistics for incoming packets.");
 DEFINE_bool(outgoing, true, "Plot statistics for outgoing packets.");
 DEFINE_bool(plot_all, true, "Plot all different data types.");
 DEFINE_bool(plot_packets,
             false,
             "Plot bar graph showing the size of each packet.");
@@ skipping 26 matching lines @@
             "Run the bandwidth estimator with the logged rtp and rtcp and plot "
             "the output.");
 DEFINE_bool(plot_network_delay_feedback,
             false,
             "Compute network delay based on sent packets and the received "
             "transport feedback.");
 DEFINE_bool(plot_fraction_loss,
             false,
             "Plot packet loss in percent for outgoing packets (as perceived by "
             "the send-side bandwidth estimator).");
+DEFINE_string(
+    force_fieldtrials,
+    "",
+    "Field trials control experimental feature code which can be forced. "
+    "E.g. running with --force_fieldtrials=WebRTC-FooFeature/Enabled/"
+    " will assign the group Enabled to field trial WebRTC-FooFeature. Multiple "
+    "trials are separated by \"/\"");
 
 int main(int argc, char* argv[]) {
   std::string program_name = argv[0];
   std::string usage =
       "A tool for visualizing WebRTC event logs.\n"
       "Example usage:\n" +
       program_name + " <logfile> | python\n" + "Run " + program_name +
       " --help for a list of command line options\n";
   google::SetUsageMessage(usage);
   google::ParseCommandLineFlags(&argc, &argv, true);
 
   if (argc != 2) {
     // Print usage information.
     std::cout << google::ProgramUsage();
     return 0;
   }
 
+  webrtc::test::InitFieldTrialsFromString(FLAGS_force_fieldtrials);
+
   std::string filename = argv[1];
 
   webrtc::ParsedRtcEventLog parsed_log;
 
   if (!parsed_log.ParseFile(filename)) {
     std::cerr << "Could not parse the entire log file." << std::endl;
     std::cerr << "Proceeding to analyze the first "
               << parsed_log.GetNumberOfEvents() << " events in the file."
               << std::endl;
   }
@@ skipping 79 matching lines @@
   }
 
   if (FLAGS_plot_all || FLAGS_plot_network_delay_feedback) {
     analyzer.CreateNetworkDelayFeedbackGraph(collection->AppendNewPlot());
   }
 
   collection->Draw();
 
   return 0;
 }