AGC2 adaptive digital dry run mode

Add the option to run the adaptive digital controller of AGC2 without
side-effects - i.e., no gain applied.

Tested: adapation verified during a video call in chromium

Bug: webrtc:7494
Change-Id: I4776f6012907d76a17a3bca89991da97dc38657f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/215964
Commit-Queue: Alessio Bazzica <alessiob@webrtc.org>
Reviewed-by: Per Ã…hgren <peah@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33875}
diff --git a/modules/audio_processing/include/audio_processing.h b/modules/audio_processing/include/audio_processing.h
index 01bb7c3..8072230 100644
--- a/modules/audio_processing/include/audio_processing.h
+++ b/modules/audio_processing/include/audio_processing.h
@@ -358,6 +358,7 @@
       } fixed_digital;
       struct AdaptiveDigital {
         bool enabled = false;
+        bool dry_run = false;
         NoiseEstimator noise_estimator = kNoiseFloor;
         int vad_reset_period_ms = 1500;
         int adjacent_speech_frames_threshold = 12;