Remove support for nack threshold.

The nack threshold feature is unlikely to provide any value, since
reordered packets are rare. This CL also removes the factory method
from the NackTracker class, since it did not add much value.

Bug: webrtc:10178
Change-Id: Ib6bece4a2d9f95bd4298799aaa15627f5c014b61
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/231953
Reviewed-by: Jakob Ivarsson <jakobi@webrtc.org>
Commit-Queue: Ivo Creusen <ivoc@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#34993}
diff --git a/modules/audio_coding/neteq/neteq_impl.cc b/modules/audio_coding/neteq/neteq_impl.cc
index ae79960..45c5229 100644
--- a/modules/audio_coding/neteq/neteq_impl.cc
+++ b/modules/audio_coding/neteq/neteq_impl.cc
@@ -10,12 +10,12 @@
 
 #include "modules/audio_coding/neteq/neteq_impl.h"
 
-
 #include <algorithm>
 #include <cstdint>
 #include <cstring>
 #include <list>
 #include <map>
+#include <memory>
 #include <utility>
 #include <vector>
 
@@ -514,8 +514,7 @@
 void NetEqImpl::EnableNack(size_t max_nack_list_size) {
   MutexLock lock(&mutex_);
   if (!nack_enabled_) {
-    const int kNackThresholdPackets = 0;
-    nack_.reset(NackTracker::Create(kNackThresholdPackets));
+    nack_ = std::make_unique<NackTracker>();
     nack_enabled_ = true;
     nack_->UpdateSampleRate(fs_hz_);
   }