Remove expired WebRTC-Audio-OpusSetSignalVoiceWithDtx

Bug: webrtc:4559
Change-Id: I060ee6a6d4bbb3329dfdf7d6819a3d346da6a8b8
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/345720
Commit-Queue: Emil Lundmark <lndmrk@webrtc.org>
Reviewed-by: Jakob Ivarsson‎ <jakobi@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#42000}

experiments/field_trials.py

diff --git a/experiments/field_trials.py b/experiments/field_trials.py
index 38113f7..27dfcb6 100755
--- a/experiments/field_trials.py
+++ b/experiments/field_trials.py
@@ -50,9 +50,6 @@
     FieldTrial('WebRTC-Audio-NetEqFecDelayAdaptation',
                'webrtc:13322',
                date(2024, 4, 1)),
-    FieldTrial('WebRTC-Audio-OpusSetSignalVoiceWithDtx',
-               'webrtc:4559',
-               date(2024, 4, 1)),
     FieldTrial('WebRTC-Audio-OpusGeneratePlc',
                'webrtc:13322',
                date(2024, 4, 1)),

modules/audio_coding/codecs/opus/opus_interface.cc

diff --git a/modules/audio_coding/codecs/opus/opus_interface.cc b/modules/audio_coding/codecs/opus/opus_interface.cc
index 64a1f59..a3ba428 100644
--- a/modules/audio_coding/codecs/opus/opus_interface.cc
+++ b/modules/audio_coding/codecs/opus/opus_interface.cc
@@ -41,9 +41,6 @@
 constexpr char kAvoidNoisePumpingDuringDtxFieldTrial[] =
     "WebRTC-Audio-OpusAvoidNoisePumpingDuringDtx";
 
-constexpr char kSetSignalVoiceWithDtxFieldTrial[] =
-    "WebRTC-Audio-OpusSetSignalVoiceWithDtx";
-
 static int FrameSizePerChannel(int frame_size_ms, int sample_rate_hz) {
   RTC_DCHECK_GT(frame_size_ms, 0);
   RTC_DCHECK_EQ(frame_size_ms % 10, 0);
@@ -361,12 +358,6 @@
 
 int16_t WebRtcOpus_EnableDtx(OpusEncInst* inst) {
   if (inst) {
-    if (webrtc::field_trial::IsEnabled(kSetSignalVoiceWithDtxFieldTrial)) {
-      int ret = ENCODER_CTL(inst, OPUS_SET_SIGNAL(OPUS_SIGNAL_VOICE));
-      if (ret != OPUS_OK) {
-        return ret;
-      }
-    }
     return ENCODER_CTL(inst, OPUS_SET_DTX(1));
   } else {
     return -1;
@@ -375,12 +366,6 @@
 
 int16_t WebRtcOpus_DisableDtx(OpusEncInst* inst) {
   if (inst) {
-    if (webrtc::field_trial::IsEnabled(kSetSignalVoiceWithDtxFieldTrial)) {
-      int ret = ENCODER_CTL(inst, OPUS_SET_SIGNAL(OPUS_AUTO));
-      if (ret != OPUS_OK) {
-        return ret;
-      }
-    }
     return ENCODER_CTL(inst, OPUS_SET_DTX(0));
   } else {
     return -1;