WebRTC AGC Hybrid experiment: wire-up AGC2 params

ConfigAutomaticGainControl now supports two additional AGC2 params that
are needed for experimentation.

Tested: checked feature activation via AECdump using appr.tc
$ out/Default/Chromium.app/Contents/MacOS/Chromium \
  --enable-features=WebrtcHybridAgc

Bug: webrtc:7494
Change-Id: I81225ebc05a66ca18e5c4b2edc350cd42f19c31a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2446052
Commit-Queue: Ale Bzk <alessiob@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#813741}

third_party/blink/renderer/modules/mediastream/media_stream_audio_processor.cc

@@ -607,6 +607,12 @@ void MediaStreamAudioProcessor::InitializeAudioProcessingModule(
           base::GetFieldTrialParamByFeatureAsInt(
               features::kWebRtcHybridAgc,
               "gain_applier_speech_frames_threshold", 1);
+      agc2_properties->max_gain_change_db_per_second =
+          base::GetFieldTrialParamByFeatureAsInt(
+              features::kWebRtcHybridAgc, "max_gain_change_db_per_second", 3);
+      agc2_properties->max_output_noise_level_dbfs =
+          base::GetFieldTrialParamByFeatureAsInt(
+              features::kWebRtcHybridAgc, "max_output_noise_level_dbfs", -50);
     }
     blink::ConfigAutomaticGainControl(
         properties.goog_auto_gain_control,

third_party/blink/renderer/platform/mediastream/media_stream_audio_processor_options.cc

@@ -240,6 +240,12 @@ void ConfigAutomaticGainControl(
 
       adaptive_digital.gain_applier_adjacent_speech_frames_threshold =
           agc2_properties->gain_applier_speech_frames_threshold;
+
+      adaptive_digital.max_gain_change_db_per_second =
+          agc2_properties->max_gain_change_db_per_second;
+
+      adaptive_digital.max_output_noise_level_dbfs =
+          agc2_properties->max_output_noise_level_dbfs;
     }
   } else if (use_fixed_digital_agc2) {
     // Experimental AGC is disabled, thus hybrid AGC is disabled. Config AGC2

third_party/blink/renderer/platform/mediastream/media_stream_audio_processor_options.h

@@ -123,6 +123,8 @@ struct PLATFORM_EXPORT AdaptiveGainController2Properties {
   int initial_saturation_margin_db;
   int extra_saturation_margin_db;
   int gain_applier_speech_frames_threshold;
+  int max_gain_change_db_per_second;
+  int max_output_noise_level_dbfs;
 };
 
 // Configures automatic gain control in `apm_config`. If `agc_enabled` is true

third_party/blink/renderer/platform/mediastream/media_stream_audio_processor_options_test.cc

@@ -49,6 +49,8 @@ TEST(ConfigAutomaticGainControlTest, EnableHybridAGC) {
   agc2_properties.initial_saturation_margin_db = 10;
   agc2_properties.extra_saturation_margin_db = 10;
   agc2_properties.gain_applier_speech_frames_threshold = 5;
+  agc2_properties.max_gain_change_db_per_second = 4;
+  agc2_properties.max_output_noise_level_dbfs = -22;
   const double compression_gain_db = 10.0;
 
   ConfigAutomaticGainControl(
@@ -82,6 +84,10 @@ TEST(ConfigAutomaticGainControlTest, EnableHybridAGC) {
                   agc2_properties.extra_saturation_margin_db);
   EXPECT_EQ(adaptive_digital.gain_applier_adjacent_speech_frames_threshold,
             agc2_properties.gain_applier_speech_frames_threshold);
+  EXPECT_FLOAT_EQ(adaptive_digital.max_gain_change_db_per_second,
+                  agc2_properties.max_gain_change_db_per_second);
+  EXPECT_FLOAT_EQ(adaptive_digital.max_output_noise_level_dbfs,
+                  agc2_properties.max_output_noise_level_dbfs);
 }
 
 TEST(PopulateApmConfigTest, DefaultWithoutConfigJson) {