Implement Theil-Sen's method for fitting a line to noisy data (used in bandwidth estimation).

webrtc/modules/congestion_controller/BUILD.gn

Index: webrtc/modules/congestion_controller/BUILD.gn
diff --git a/webrtc/modules/congestion_controller/BUILD.gn b/webrtc/modules/congestion_controller/BUILD.gn
index 09b33881c84374081bf64e6a0752c1218ec9d6eb..b0cdd8c324dadd4efed1d6829fdf02033c114243 100644
--- a/webrtc/modules/congestion_controller/BUILD.gn
+++ b/webrtc/modules/congestion_controller/BUILD.gn
@@ -20,6 +20,8 @@ rtc_static_library("congestion_controller") {
     "probe_controller.h",
     "probing_interval_estimator.cc",
     "probing_interval_estimator.h",
+    "theil_sen_estimator.cc",
+    "theil_sen_estimator.h",
     "transport_feedback_adapter.cc",
     "transport_feedback_adapter.h",
     "trendline_estimator.cc",
@@ -41,6 +43,7 @@ rtc_static_library("congestion_controller") {
   }
 
   deps = [
+    "../../base:rtc_analytics",
     "../bitrate_controller",
     "../pacing",
   ]