Test and fix for huge bwe drop after alr state.

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 ef452970318f71fc42c3764f90ec8a7bbb134469..eade5598cb3d16864b96dbc7443c1e31109b8dce 100644
--- a/webrtc/modules/congestion_controller/BUILD.gn
+++ b/webrtc/modules/congestion_controller/BUILD.gn
@@ -10,8 +10,10 @@ import("../../webrtc.gni")
 
 rtc_static_library("congestion_controller") {
   sources = [
-    "acknowledge_bitrate_estimator.cc",
-    "acknowledge_bitrate_estimator.h",
+    "acknowledged_bitrate_estimator.cc",
+    "acknowledged_bitrate_estimator.h",
+    "bitrate_estimator.cc",
+    "bitrate_estimator.h",
     "congestion_controller.cc",
     "delay_based_bwe.cc",
     "delay_based_bwe.h",
@@ -73,6 +75,7 @@ if (rtc_include_tests) {
       visibility = [ "//webrtc/modules:modules_unittests" ]
     }
     sources = [
+      "acknowledged_bitrate_estimator_unittest.cc",
       "congestion_controller_unittest.cc",
       "congestion_controller_unittests_helper.cc",
       "congestion_controller_unittests_helper.h",
@@ -90,6 +93,7 @@ if (rtc_include_tests) {
       ":mock_congestion_controller",
       "../../base:rtc_base",
       "../../base:rtc_base_approved",
+      "../../base:rtc_base_tests_utils",
       "../../system_wrappers:system_wrappers",
       "../../test:field_trial",
       "../../test:test_support",