Fix race / crash in OnNetworkRouteChanged().

webrtc/modules/congestion_controller/delay_based_bwe.h

Index: webrtc/modules/congestion_controller/delay_based_bwe.h
diff --git a/webrtc/modules/congestion_controller/delay_based_bwe.h b/webrtc/modules/congestion_controller/delay_based_bwe.h
index 3e0a0149a41e1019bd0843a49f5a29de2ca74f39..424431636f5798d22ee1db16aa792cd1cc09d22b 100644
--- a/webrtc/modules/congestion_controller/delay_based_bwe.h
+++ b/webrtc/modules/congestion_controller/delay_based_bwe.h
@@ -18,7 +18,7 @@
 
 #include "webrtc/base/checks.h"
 #include "webrtc/base/constructormagic.h"
-#include "webrtc/base/criticalsection.h"
+#include "webrtc/base/optional.h"
 #include "webrtc/base/rate_statistics.h"
 #include "webrtc/base/thread_checker.h"
 #include "webrtc/modules/congestion_controller/probe_bitrate_estimator.h"
@@ -27,46 +27,42 @@
 #include "webrtc/modules/remote_bitrate_estimator/inter_arrival.h"
 #include "webrtc/modules/remote_bitrate_estimator/overuse_detector.h"
 #include "webrtc/modules/remote_bitrate_estimator/overuse_estimator.h"
-#include "webrtc/system_wrappers/include/critical_section_wrapper.h"
 
 namespace webrtc {
 
-class DelayBasedBwe : public RemoteBitrateEstimator {
+class DelayBasedBwe {
  public:
-  DelayBasedBwe(RemoteBitrateObserver* observer, Clock* clock);
+  static const int64_t kStreamTimeOutMs = 2000;
+
+  struct Result {
+    Result() : updated(false), probe(false), target_bitrate_bps(0) {}
+    Result(bool probe, uint32_t target_bitrate_bps)
+        : updated(true), probe(probe), target_bitrate_bps(target_bitrate_bps) {}
+    bool updated;
+    bool probe;
+    uint32_t target_bitrate_bps;
+  };
+
+  explicit DelayBasedBwe(Clock* clock);
   virtual ~DelayBasedBwe() {}
 
-  void IncomingPacketFeedbackVector(
-      const std::vector<PacketInfo>& packet_feedback_vector) override;
-  void OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms) override;
+  Result IncomingPacketFeedbackVector(
+      const std::vector<PacketInfo>& packet_feedback_vector);
+  void OnRttUpdate(int64_t avg_rtt_ms, int64_t max_rtt_ms);
   bool LatestEstimate(std::vector<uint32_t>* ssrcs,
-                      uint32_t* bitrate_bps) const override;
-  void SetMinBitrate(int min_bitrate_bps) override;
-
-  // Required by RemoteBitrateEstimator but does nothing.
-  void Process() override;
-  // Required by RemoteBitrateEstimator but does nothing.
-  int64_t TimeUntilNextProcess() override;
-  // Required by RemoteBitrateEstimator but does nothing.
-  void RemoveStream(uint32_t ssrc) override;
-  void IncomingPacket(int64_t arrival_time_ms,
-                      size_t payload_size,
-                      const RTPHeader& header) override {
-    RTC_NOTREACHED();
-  }
+                      uint32_t* bitrate_bps) const;
+  void SetMinBitrate(int min_bitrate_bps);
 
  private:
-  void IncomingPacketInfo(const PacketInfo& info);
+  Result IncomingPacketInfo(const PacketInfo& info);
   // Updates the current remote rate estimate and returns true if a valid
   // estimate exists.
   bool UpdateEstimate(int64_t packet_arrival_time_ms,
                       int64_t now_ms,
-                      uint32_t* target_bitrate_bps)
-      EXCLUSIVE_LOCKS_REQUIRED(crit_);
+                      uint32_t* target_bitrate_bps);
 
   rtc::ThreadChecker network_thread_;
   Clock* const clock_;
-  RemoteBitrateObserver* const observer_;
   std::unique_ptr<InterArrival> inter_arrival_;
   std::unique_ptr<OveruseEstimator> estimator_;
   OveruseDetector detector_;
@@ -74,10 +70,8 @@ class DelayBasedBwe : public RemoteBitrateEstimator {
   int64_t last_update_ms_;
   int64_t last_seen_packet_ms_;
   bool uma_recorded_;
-
-  rtc::CriticalSection crit_;
-  AimdRateControl remote_rate_ GUARDED_BY(&crit_);
-  ProbeBitrateEstimator probe_bitrate_estimator_ GUARDED_BY(&crit_);
+  AimdRateControl remote_rate_;
+  ProbeBitrateEstimator probe_bitrate_estimator_;
 
   RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(DelayBasedBwe);
 };