Reland "Structured ICE logging via RtcEventLog."

This is a reland of eed5aa8904d09179971d3f4e7e10c109d7c62bfc
Original change's description:
> Structured ICE logging via RtcEventLog.
>
> This change list contains the structured logging module for ICE using
> the RtcEventLog infrastructure, and also extension to the log parser
> and analyzer.
>
> Bug: None
> Change-Id: I6539cf282155c2cde4d3161c53500c0746671a02
> Reviewed-on: https://webrtc-review.googlesource.com/34622
> Commit-Queue: Qingsi Wang <qingsi@google.com>
> Reviewed-by: Björn Terelius <terelius@webrtc.org>
> Reviewed-by: Peter Thatcher <pthatcher@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#21816}

TBR=pthatcher@webrtc.org,terelius@webrtc.org,deadbeef@webrtc.org

Bug: None
Change-Id: I3df585bf636315ceb0273967146111346a83be86
Reviewed-on: https://webrtc-review.googlesource.com/47545
Commit-Queue: Qingsi Wang <qingsi@google.com>
Reviewed-by: Qingsi Wang <qingsi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21881}
diff --git a/rtc_tools/event_log_visualizer/main.cc b/rtc_tools/event_log_visualizer/main.cc
index 4a6ec64..2e7a79e 100644
--- a/rtc_tools/event_log_visualizer/main.cc
+++ b/rtc_tools/event_log_visualizer/main.cc
@@ -115,6 +115,12 @@
 DEFINE_bool(plot_audio_jitter_buffer,
             false,
             "Plot the audio jitter buffer delay profile.");
+DEFINE_bool(plot_ice_candidate_pair_config,
+            false,
+            "Plot the ICE candidate pair config events.");
+DEFINE_bool(plot_ice_connectivity_check,
+            false,
+            "Plot the ICE candidate pair connectivity checks.");
 
 DEFINE_string(
     force_fieldtrials,
@@ -318,6 +324,13 @@
                                           collection->AppendNewPlot());
   }
 
+  if (FLAG_plot_ice_candidate_pair_config) {
+    analyzer.CreateIceCandidatePairConfigGraph(collection->AppendNewPlot());
+  }
+  if (FLAG_plot_ice_connectivity_check) {
+    analyzer.CreateIceConnectivityCheckGraph(collection->AppendNewPlot());
+  }
+
   collection->Draw();
 
   if (FLAG_print_triage_notifications) {
@@ -356,4 +369,6 @@
   FLAG_plot_audio_encoder_dtx = setting;
   FLAG_plot_audio_encoder_num_channels = setting;
   FLAG_plot_audio_jitter_buffer = setting;
+  FLAG_plot_ice_candidate_pair_config = setting;
+  FLAG_plot_ice_connectivity_check = setting;
 }