Implement periodic bandwidth probing in application-limited region.

webrtc/modules/congestion_controller/probe_controller.h

Index: webrtc/modules/congestion_controller/probe_controller.h
diff --git a/webrtc/modules/congestion_controller/probe_controller.h b/webrtc/modules/congestion_controller/probe_controller.h
index e60a007b9d94402253d1982b27f3649f79bb6f32..bcdc2fdf0353a5bba736227454409a804c1949c6 100644
--- a/webrtc/modules/congestion_controller/probe_controller.h
+++ b/webrtc/modules/congestion_controller/probe_controller.h
@@ -13,6 +13,7 @@
 
 #include <initializer_list>
 
+#include "webrtc/base/optional.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/common_types.h"
 #include "webrtc/modules/pacing/paced_sender.h"
@@ -36,6 +37,9 @@ class ProbeController {
 
   void SetEstimatedBitrate(int bitrate_bps);
 
+  void EnablePeriodicAlrProbing(bool enable);
+  void Process();
+
  private:
   enum class State {
     // Initial state where no probing has been triggered yet.
@@ -47,7 +51,8 @@ class ProbeController {
   };
 
   void InitiateExponentialProbing() EXCLUSIVE_LOCKS_REQUIRED(critsect_);
-  void InitiateProbing(std::initializer_list<int> bitrates_to_probe,
+  void InitiateProbing(int64_t now_ms,
+                       std::initializer_list<int> bitrates_to_probe,
                        int min_bitrate_to_probe_further_bps)
       EXCLUSIVE_LOCKS_REQUIRED(critsect_);
 
@@ -62,6 +67,7 @@ class ProbeController {
   int start_bitrate_bps_ GUARDED_BY(critsect_);
   int max_bitrate_bps_ GUARDED_BY(critsect_);
   int64_t last_alr_probing_time_ GUARDED_BY(critsect_);
+  bool enable_periodic_alr_probing_ GUARDED_BY(critsect_);
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(ProbeController);
 };