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

webrtc/modules/audio_processing/audio_processing_impl.h

Index: webrtc/modules/audio_processing/audio_processing_impl.h
diff --git a/webrtc/modules/audio_processing/audio_processing_impl.h b/webrtc/modules/audio_processing/audio_processing_impl.h
index fa07281852d862ab923e4254e414b2e8fec13878..b21d5be7f101214d758b28d3cc9f72b3c3554f38 100644
--- a/webrtc/modules/audio_processing/audio_processing_impl.h
+++ b/webrtc/modules/audio_processing/audio_processing_impl.h
@@ -16,6 +16,7 @@
 #include <string>
 #include <vector>
 
+#include "webrtc/base/gtest_prod_util.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/modules/audio_processing/audio_buffer.h"
@@ -129,6 +130,7 @@ class AudioProcessingImpl : public AudioProcessing {
       EXCLUSIVE_LOCKS_REQUIRED(crit_render_, crit_capture_);
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(ApmConfiguration, LevelController);
   struct ApmPublicSubmodules;
   struct ApmPrivateSubmodules;
 
@@ -282,6 +284,9 @@ class AudioProcessingImpl : public AudioProcessing {
   rtc::CriticalSection crit_render_ ACQUIRED_BEFORE(crit_capture_);
   rtc::CriticalSection crit_capture_;
 
+  // Struct containing the Config specifying the behavior of APM.
+  AudioProcessing::Config config_;
+
   // Class containing information about what submodules are active.
   ApmSubmoduleStates submodule_states_;