Probing: Add support for exponential startup probing

Adds support for exponentially probing the bandwidth at start-up to allow
ramp-up to real capacity of the network.

BUG=webrtc:6332
R=philipel@webrtc.org, stefan@webrtc.org

Review URL: https://codereview.webrtc.org/2235373004 .

Cr-Commit-Position: refs/heads/master@{#14189}
diff --git a/webrtc/tools/event_log_visualizer/analyzer.cc b/webrtc/tools/event_log_visualizer/analyzer.cc
index 5a8733c..eab4dcf 100644
--- a/webrtc/tools/event_log_visualizer/analyzer.cc
+++ b/webrtc/tools/event_log_visualizer/analyzer.cc
@@ -1008,7 +1008,7 @@
   }
 
   SimulatedClock clock(0);
-  TransportFeedbackAdapter feedback_adapter(nullptr, &clock);
+  TransportFeedbackAdapter feedback_adapter(&clock);
 
   TimeSeries time_series;
   time_series.label = "Network Delay Change";