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 172da0891f3bcd362b4796b23a3b4b59b0b9a6f7..902e177ae829447e6b94725ebbea42fd3254003d 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 = -6.0206;
     } level_controller;
   };