Make LevelEstimation not a ProcessingComponent.

BUG=webrtc:5355

Review URL: https://codereview.webrtc.org/1523483002

Cr-Commit-Position: refs/heads/master@{#11033}
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.h b/webrtc/modules/audio_processing/audio_processing_impl.h
index c4d5f08..eb34976 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.h
+++ b/webrtc/modules/audio_processing/audio_processing_impl.h
@@ -185,6 +185,8 @@
       EXCLUSIVE_LOCKS_REQUIRED(crit_capture_);
   void InitializeNoiseSuppression()
       EXCLUSIVE_LOCKS_REQUIRED(crit_capture_);
+  void InitializeLevelEstimator()
+      EXCLUSIVE_LOCKS_REQUIRED(crit_capture_);
   int InitializeLocked(const ProcessingConfig& config)
       EXCLUSIVE_LOCKS_REQUIRED(crit_render_, crit_capture_);