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

webrtc/modules/audio_processing/level_controller/peak_level_estimator.h

 /*
  *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MODULES_AUDIO_PROCESSING_LEVEL_CONTROLLER_PEAK_LEVEL_ESTIMATOR_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_LEVEL_CONTROLLER_PEAK_LEVEL_ESTIMATOR_H_
 
 #include "webrtc/base/constructormagic.h"
+#include "webrtc/base/gtest_prod_util.h"
+#include "webrtc/modules/audio_processing/level_controller/lc_constants.h"
 #include "webrtc/modules/audio_processing/level_controller/signal_classifier.h"
 
 namespace webrtc {
 
 class PeakLevelEstimator {
  public:
   PeakLevelEstimator();
   ~PeakLevelEstimator();
   void Initialize();
   float Analyze(SignalClassifier::SignalType signal_type,
                 float frame_peak_level);
+  // 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].
+  void SetInitialPeakLevel(float level);
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(LevelControllerConfig, InitialLevel);
   float peak_level_;
+  float initial_peak_level_ = kTargetLcPeakLevel;

[the sun, 2016/09/16 12:40:25]

Is this default value really needed? Won't it be set up from the LC default
config and ApplyConfig when the LC is initialized?

[peah-webrtc, 2016/09/19 16:37:10]

Not in the way it is now, as it basically constitutes the cached value from the
config which is reused each time the level controller is reinitialized (for
reasons such as sample rate change, changes in the number of channels, etc.)

This is, however, changed in response to another of your comments.

Done.

   int hold_counter_;
   bool initialization_phase_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(PeakLevelEstimator);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_LEVEL_CONTROLLER_PEAK_LEVEL_ESTIMATOR_H_