Add a function for enabling the congestion window and pushback controller in the webrtc::SendSideCongestionController.

Bug: webrtc:9923
Change-Id: Id01ebd7237ba33f34003aa9560405a13da7580e2
Reviewed-on: https://webrtc-review.googlesource.com/c/107893
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Ying Wang <yinwa@webrtc.org>
Commit-Queue: Erik Varga <erikvarga@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#25393}

modules/congestion_controller/goog_cc/congestion_window_pushback_controller.cc

@@ -47,6 +47,10 @@ CongestionWindowPushbackController::CongestionWindowPushbackController() {
   }
 }
 
+CongestionWindowPushbackController::CongestionWindowPushbackController(
+    uint32_t min_pushback_target_bitrate_bps)
+    : min_pushback_target_bitrate_bps_(min_pushback_target_bitrate_bps) {}
+
 void CongestionWindowPushbackController::UpdateOutstandingData(
     size_t outstanding_bytes) {
   outstanding_bytes_ = outstanding_bytes;

modules/congestion_controller/goog_cc/congestion_window_pushback_controller.h

@@ -23,6 +23,8 @@ namespace webrtc {
 class CongestionWindowPushbackController {
  public:
   CongestionWindowPushbackController();
+  explicit CongestionWindowPushbackController(
+      uint32_t min_pushback_target_bitrate_bps);
   void UpdateOutstandingData(size_t outstanding_bytes);
   void UpdateMaxOutstandingData(size_t max_outstanding_bytes);
   uint32_t UpdateTargetBitrate(uint32_t bitrate_bps);

modules/congestion_controller/include/send_side_congestion_controller.h

@@ -113,6 +113,9 @@ class SendSideCongestionController
 
   void SetAllocatedBitrateWithoutFeedback(uint32_t bitrate_bps) override;
 
+  void EnableCongestionWindowPushback(int64_t accepted_queue_ms,
+                                      uint32_t min_pushback_target_bitrate_bps);
+
  private:
   void MaybeTriggerOnNetworkChanged();
 
@@ -161,7 +164,7 @@ class SendSideCongestionController
   bool pacer_pushback_experiment_ = false;
   float encoding_rate_ = 1.0;
 
-  const std::unique_ptr<CongestionWindowPushbackController>
+  std::unique_ptr<CongestionWindowPushbackController>
       congestion_window_pushback_controller_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(SendSideCongestionController);

modules/congestion_controller/send_side_congestion_controller.cc

@@ -164,6 +164,23 @@ SendSideCongestionController::SendSideCongestionController(
 
 SendSideCongestionController::~SendSideCongestionController() {}
 
+void SendSideCongestionController::EnableCongestionWindowPushback(
+    int64_t accepted_queue_ms,
+    uint32_t min_pushback_target_bitrate_bps) {
+  RTC_DCHECK(!congestion_window_pushback_controller_)
+      << "The congestion pushback is already enabled.";
+  RTC_CHECK_GE(accepted_queue_ms, 0)
+      << "Accepted must be greater than or equal to 0.";
+  RTC_CHECK_GE(min_pushback_target_bitrate_bps, 0)
+      << "Min pushback target bitrate must be greater than or equal to 0.";
+
+  in_cwnd_experiment_ = true;
+  accepted_queue_ms_ = accepted_queue_ms;
+  congestion_window_pushback_controller_ =
+      absl::make_unique<CongestionWindowPushbackController>(
+          min_pushback_target_bitrate_bps);
+}
+
 void SendSideCongestionController::RegisterPacketFeedbackObserver(
     PacketFeedbackObserver* observer) {
   transport_feedback_adapter_.RegisterPacketFeedbackObserver(observer);