Support REMB in combination with send-side BWE.

BUG=webrtc:4173

Review URL: https://codereview.webrtc.org/1581113006

Cr-Commit-Position: refs/heads/master@{#11322}
diff --git a/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc b/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
index f8fd2bb..da51c6f 100644
--- a/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
+++ b/webrtc/modules/bitrate_controller/bitrate_controller_impl.cc
@@ -143,6 +143,15 @@
   MaybeTriggerOnNetworkChanged();
 }
 
+void BitrateControllerImpl::UpdateDelayBasedEstimate(uint32_t bitrate_bps) {
+  {
+    rtc::CritScope cs(&critsect_);
+    bandwidth_estimation_.UpdateDelayBasedEstimate(clock_->TimeInMilliseconds(),
+                                                   bitrate_bps);
+  }
+  MaybeTriggerOnNetworkChanged();
+}
+
 int64_t BitrateControllerImpl::TimeUntilNextProcess() {
   const int64_t kBitrateControllerUpdateIntervalMs = 25;
   rtc::CritScope cs(&critsect_);