Fix ubsan warnings in BWE tests.

webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc

Index: webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
diff --git a/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc b/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
index 6166ff8c2d409ecbbe290025674257c140a76553..066b4b5e35301190ae34e31d701124fb6feecfdc 100644
--- a/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
+++ b/webrtc/modules/remote_bitrate_estimator/test/estimators/nada.cc
@@ -178,7 +178,8 @@ void NadaBweSender::GiveFeedback(const FeedbackPacket& feedback) {
 
   // Following parameters might be optimized.
   const int64_t kQueuingDelayUpperBoundMs = 10;
-  const float kDerivativeUpperBound = 10.0f / min_feedback_delay_ms_;
+  const float kDerivativeUpperBound =
+      10.0f / std::max<int64_t>(1, min_feedback_delay_ms_);
   // In the modified version, a higher kMinUpperBound allows a higher d_hat
   // upper bound for calling AcceleratedRampUp.
   const float kProportionalityDelayBits = 20.0f;