From dda037db07df96f62df32c47637fa55d068516ee Mon Sep 17 00:00:00 2001
From: Danil Chapovalov <danilchap@webrtc.org>
Date: Tue, 9 Jan 2024 11:48:13 +0100
Subject: [PATCH] Remove unused field trial DisablePacerEmergencyStop

This field trial was added 5 years ago in
https://webrtc-review.googlesource.com/c/src/+/111883
probably as a safe guard, but looks never used.

Bug: webrtc:11503
Change-Id: Ia9544b652b25fad4c614d66fe020f3d994c96505
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/333380
Commit-Queue: Danil Chapovalov <danilchap@webrtc.org>
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#41490}
---
 experiments/field_trials.py                    |  3 ---
 modules/congestion_controller/rtp/BUILD.gn     |  1 -
 .../rtp/control_handler.cc                     | 18 ++----------------
 .../rtp/control_handler.h                      |  6 +++---
 4 files changed, 5 insertions(+), 23 deletions(-)

diff --git a/experiments/field_trials.py b/experiments/field_trials.py
index 7e1643647d..82761a2659 100755
--- a/experiments/field_trials.py
+++ b/experiments/field_trials.py
@@ -568,9 +568,6 @@ POLICY_EXEMPT_FIELD_TRIALS: FrozenSet[FieldTrial] = frozenset([
     FieldTrial('WebRTC-DependencyDescriptorAdvertised',
                'webrtc:10342',
                date(2024, 4, 1)),
-    FieldTrial('WebRTC-DisablePacerEmergencyStop',
-               '',
-               date(2024, 4, 1)),
     FieldTrial('WebRTC-DisableUlpFecExperiment',
                '',
                date(2024, 4, 1)),
diff --git a/modules/congestion_controller/rtp/BUILD.gn b/modules/congestion_controller/rtp/BUILD.gn
index cd13332b7f..8ec755e1aa 100644
--- a/modules/congestion_controller/rtp/BUILD.gn
+++ b/modules/congestion_controller/rtp/BUILD.gn
@@ -34,7 +34,6 @@ rtc_library("control_handler") {
     "../../../rtc_base:safe_conversions",
     "../../../rtc_base:safe_minmax",
     "../../../rtc_base/system:no_unique_address",
-    "../../../system_wrappers:field_trial",
     "../../pacing",
   ]
   absl_deps = [ "//third_party/abseil-cpp/absl/types:optional" ]
diff --git a/modules/congestion_controller/rtp/control_handler.cc b/modules/congestion_controller/rtp/control_handler.cc
index da6451c97e..357a0f0798 100644
--- a/modules/congestion_controller/rtp/control_handler.cc
+++ b/modules/congestion_controller/rtp/control_handler.cc
@@ -18,21 +18,8 @@
 #include "rtc_base/logging.h"
 #include "rtc_base/numerics/safe_conversions.h"
 #include "rtc_base/numerics/safe_minmax.h"
-#include "system_wrappers/include/field_trial.h"
 
 namespace webrtc {
-namespace {
-
-// By default, pacer emergency stops encoder when buffer reaches a high level.
-bool IsPacerEmergencyStopDisabled() {
-  return field_trial::IsEnabled("WebRTC-DisablePacerEmergencyStop");
-}
-
-}  // namespace
-CongestionControlHandler::CongestionControlHandler()
-    : disable_pacer_emergency_stop_(IsPacerEmergencyStopDisabled()) {}
-
-CongestionControlHandler::~CongestionControlHandler() {}
 
 void CongestionControlHandler::SetTargetRate(
     TargetTransferRate new_target_rate) {
@@ -60,9 +47,8 @@ absl::optional<TargetTransferRate> CongestionControlHandler::GetUpdate() {
   bool pause_encoding = false;
   if (!network_available_) {
     pause_encoding = true;
-  } else if (!disable_pacer_emergency_stop_ &&
-             pacer_expected_queue_ms_ >
-                 PacingController::kMaxExpectedQueueLength.ms()) {
+  } else if (pacer_expected_queue_ms_ >
+             PacingController::kMaxExpectedQueueLength.ms()) {
     pause_encoding = true;
   }
   if (pause_encoding)
diff --git a/modules/congestion_controller/rtp/control_handler.h b/modules/congestion_controller/rtp/control_handler.h
index d8e7263a02..649d2f911e 100644
--- a/modules/congestion_controller/rtp/control_handler.h
+++ b/modules/congestion_controller/rtp/control_handler.h
@@ -28,12 +28,13 @@ namespace webrtc {
 // destruction unless members are properly ordered.
 class CongestionControlHandler {
  public:
-  CongestionControlHandler();
-  ~CongestionControlHandler();
+  CongestionControlHandler() = default;
 
   CongestionControlHandler(const CongestionControlHandler&) = delete;
   CongestionControlHandler& operator=(const CongestionControlHandler&) = delete;
 
+  ~CongestionControlHandler() = default;
+
   void SetTargetRate(TargetTransferRate new_target_rate);
   void SetNetworkAvailability(bool network_available);
   void SetPacerQueue(TimeDelta expected_queue_time);
@@ -45,7 +46,6 @@ class CongestionControlHandler {
   bool network_available_ = true;
   bool encoder_paused_in_last_report_ = false;
 
-  const bool disable_pacer_emergency_stop_;
   int64_t pacer_expected_queue_ms_ = 0;
 
   RTC_NO_UNIQUE_ADDRESS SequenceChecker sequenced_checker_;