Introduced new scheme for controlling the functionality inside the audio processing module

webrtc/modules/audio_processing/level_controller/level_controller.cc

Index: webrtc/modules/audio_processing/level_controller/level_controller.cc
diff --git a/webrtc/modules/audio_processing/level_controller/level_controller.cc b/webrtc/modules/audio_processing/level_controller/level_controller.cc
index 2294396607505f86511e83f12f110a8a636601bf..c0edeb91c50f5a472019f07eb45ce97910d9ea12 100644
--- a/webrtc/modules/audio_processing/level_controller/level_controller.cc
+++ b/webrtc/modules/audio_processing/level_controller/level_controller.cc
@@ -262,4 +262,17 @@ void LevelController::Process(AudioBuffer* audio) {
                         audio->channels_f()[0], *sample_rate_hz_, 1);
 }
 
+std::string LevelController::ToString(
+    const AudioProcessing::Config::LevelController& config) {
+  std::stringstream ss;
+  ss << "{"
+     << "enabled: " << (config.enabled ? "true" : "false") << "}";
+  return ss.str();
+}
+
+bool LevelController::Validate(
+    const AudioProcessing::Config::LevelController& config) {
+  return true;
+}
+
 }  // namespace webrtc