Reland of added functionality for specifying the initial signal level to use for the gain estimation

webrtc/modules/audio_processing/include/audio_processing.h

Index: webrtc/modules/audio_processing/include/audio_processing.h
diff --git a/webrtc/modules/audio_processing/include/audio_processing.h b/webrtc/modules/audio_processing/include/audio_processing.h
index 2b447c4ade10c4bf110195f06bd07573bcf9debf..b5d2aa22c0348cd4da2011fb7a67803d80862337 100644
--- a/webrtc/modules/audio_processing/include/audio_processing.h
+++ b/webrtc/modules/audio_processing/include/audio_processing.h
@@ -252,6 +252,11 @@ class AudioProcessing {
   struct Config {
     struct LevelController {
       bool enabled = false;
+
+      // Sets the initial peak level to use inside the level controller in order
+      // to compute the signal gain. The unit for the peak level is dBFS and
+      // the allowed range is [-100, 0].
+      float initial_peak_level_dbfs = -6.0206f;
     } level_controller;
   };