Changing the pre echo configuration default.

Bug: webrtc:14205
Change-Id: I17add3bf19c599f170ffe98d0da0a561794591c1
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/309481
Commit-Queue: Jesus de Vicente Pena <[email protected]>
Reviewed-by: Per Åhgren <[email protected]>
Cr-Commit-Position: refs/heads/main@{#40319}

Author: Jesús de Vicente Peña

modules/audio_processing/aec3/matched_filter.cc

@@ -109,14 +109,16 @@ size_t ComputePreEchoLag(
 }
 
 webrtc::MatchedFilter::PreEchoConfiguration FetchPreEchoConfiguration() {
-  float threshold = 0.5f;
-  int mode = 0;
+  constexpr float kDefaultThreshold = 0.5f;
+  constexpr int kDefaultMode = 3;
+  float threshold = kDefaultThreshold;
+  int mode = kDefaultMode;
   const std::string pre_echo_configuration_field_trial =
       webrtc::field_trial::FindFullName("WebRTC-Aec3PreEchoConfiguration");
   webrtc::FieldTrialParameter<double> threshold_field_trial_parameter(
-      /*key=*/"threshold", /*default_value=*/threshold);
+      /*key=*/"threshold", /*default_value=*/kDefaultThreshold);
   webrtc::FieldTrialParameter<int> mode_field_trial_parameter(
-      /*key=*/"mode", /*default_value=*/mode);
+      /*key=*/"mode", /*default_value=*/kDefaultMode);
   webrtc::ParseFieldTrial(
       {&threshold_field_trial_parameter, &mode_field_trial_parameter},
       pre_echo_configuration_field_trial);

modules/audio_processing/aec3/matched_filter_unittest.cc

@@ -584,7 +584,7 @@ TEST(MatchedFilterFieldTrialTest, PreEchoConfigurationTest) {
 
 TEST(MatchedFilterFieldTrialTest, WrongPreEchoConfigurationTest) {
   constexpr float kDefaultThreshold = 0.5f;
-  constexpr int kDefaultMode = 0;
+  constexpr int kDefaultMode = 3;
   float threshold_in = -0.1f;
   int mode_in = 5;
   rtc::StringBuilder field_trial_name;