libwebrtc fixes and updates

- Fix calculation of feedback min_pending_time in goog_cc
  - Fixes #849
  - Commit in libwebrtc: https://webrtc.googlesource.com/src/+/d65dc979b17cdc7cd359aada59e5bce8a6f1b8ce%5E%21/
-
Fix signed-to-unsigned overflow in send_side_bandwidth_estimation.cc
  - Fixes #872
  - Issue in libwebrtc: https://bugs.chromium.org/p/webrtc/issues/detail?id=14272
  - Commit in libwebrtc: https://webrtc.googlesource.com/src/+/9804aa5f6ad26a45338d685da66497c3bbd88ca6%5E%21/

NOTE: Some changes are already present in ongoing PR #922 but it's not yet merged.

Author: ibc

worker/deps/libwebrtc/libwebrtc/modules/bitrate_controller/send_side_bandwidth_estimation.cc

@@ -382,26 +382,29 @@ void SendSideBandwidthEstimation::UpdatePacketsLost(int packets_lost,
 
   // Check sequence number diff and weight loss report
   if (number_of_packets > 0) {
-    // Accumulate reports.
-    lost_packets_since_last_loss_update_ += packets_lost;
-    expected_packets_since_last_loss_update_ += number_of_packets;
+    int64_t expected =
+      expected_packets_since_last_loss_update_ + number_of_packets;
 
     // Don't generate a loss rate until it can be based on enough packets.
-    if (expected_packets_since_last_loss_update_ < kLimitNumPackets)
+    if (expected < kLimitNumPackets) {
+      // Accumulate reports.
+      expected_packets_since_last_loss_update_ = expected;
+      lost_packets_since_last_loss_update_ += packets_lost;
       return;
+    }
 
     has_decreased_since_last_fraction_loss_ = false;
-    int64_t lost_q8 = lost_packets_since_last_loss_update_ << 8;
-    int64_t expected = expected_packets_since_last_loss_update_;
+    int64_t lost_q8 =
+      std::max<int64_t>(lost_packets_since_last_loss_update_ + packets_lost, 0) << 8;
     last_fraction_loss_ = std::min<int>(lost_q8 / expected, 255);
 
     // Reset accumulators.
-
     lost_packets_since_last_loss_update_ = 0;
     expected_packets_since_last_loss_update_ = 0;
     last_loss_packet_report_ = at_time;
     UpdateEstimate(at_time);
   }
+
   UpdateUmaStatsPacketsLost(at_time, packets_lost);
 }
 

worker/deps/libwebrtc/libwebrtc/modules/congestion_controller/goog_cc/goog_cc_network_control.cc

@@ -431,7 +431,7 @@ NetworkControlUpdate GoogCcNetworkController::OnTransportPacketsFeedback(
   for (const auto& feedback : feedbacks) {
     TimeDelta feedback_rtt =
         report.feedback_time - feedback.sent_packet.send_time;
-    TimeDelta min_pending_time = feedback.receive_time - max_recv_time;
+    TimeDelta min_pending_time = max_recv_time - feedback.receive_time;
     TimeDelta propagation_rtt = feedback_rtt - min_pending_time;
     max_feedback_rtt = std::max(max_feedback_rtt, feedback_rtt);
     min_propagation_rtt = std::min(min_propagation_rtt, propagation_rtt);