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

webrtc/modules/audio_processing/level_controller/level_controller.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_LEVEL_CONTROLLER_H_
 #define WEBRTC_MODULES_AUDIO_PROCESSING_LEVEL_CONTROLLER_LEVEL_CONTROLLER_H_
 
 #include <memory>
 #include <vector>
 
 #include "webrtc/base/constructormagic.h"
+#include "webrtc/base/gtest_prod_util.h"
 #include "webrtc/base/optional.h"
 #include "webrtc/modules/audio_processing/include/audio_processing.h"
 #include "webrtc/modules/audio_processing/level_controller/gain_applier.h"
 #include "webrtc/modules/audio_processing/level_controller/gain_selector.h"
 #include "webrtc/modules/audio_processing/level_controller/noise_level_estimator.h"
 #include "webrtc/modules/audio_processing/level_controller/peak_level_estimator.h"
 #include "webrtc/modules/audio_processing/level_controller/saturating_gain_estimator.h"
 #include "webrtc/modules/audio_processing/level_controller/signal_classifier.h"
 
 namespace webrtc {
 
 class ApmDataDumper;
 class AudioBuffer;
 
 class LevelController {
  public:
   LevelController();
   ~LevelController();
 
   void Initialize(int sample_rate_hz);
   void Process(AudioBuffer* audio);
   float GetLastGain() { return last_gain_; }
 
+  // TODO(peah): This method is a temporary solution as the the aim is to
+  // instead apply the config inside the constructor. Therefore this is likely
+  // to change.
+  void ApplyConfig(const AudioProcessing::Config::LevelController& config);
   // Validates a config.
   static bool Validate(const AudioProcessing::Config::LevelController& config);
   // Dumps a config to a string.
   static std::string ToString(
       const AudioProcessing::Config::LevelController& config);
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(LevelControllerConfig, InitialLevel);

[the sun, 2016/09/30 08:51:16]

You should try to make do without declaring all tests as friends. This pattern
makes sense for the APM, since the APM interface is harder to change and the
impl is very large at the moment, but this is fairly new code, and internal, so
it can be changed to make testing easier.

If absolutely necessary, add a "NnnForTesting()" utility function. Exposing ALL
the internals of the class to tests blurs the expectations of the test and class
interface.

[peah-webrtc, 2016/10/03 09:52:14]

I fully agree  with you your comment about FRIEND classes. 

I fully agree  with you your comment about FRIEND classes. 
After offline discussions we decided to not explicitly verify that the specified
settings take effect, and instead leave that to the bitexactness tests.
I have changed the code accordingly. PTAL.

   class Metrics {
    public:
     Metrics() { Initialize(AudioProcessing::kSampleRate48kHz); }
     void Initialize(int sample_rate_hz);
     void Update(float long_term_peak_level,
                 float noise_level,
                 float gain,
                 float frame_peak_level);
 
    private:
@@ skipping 15 matching lines @@
   SignalClassifier signal_classifier_;
   NoiseLevelEstimator noise_level_estimator_;
   PeakLevelEstimator peak_level_estimator_;
   SaturatingGainEstimator saturating_gain_estimator_;
   Metrics metrics_;
   rtc::Optional<int> sample_rate_hz_;
   static int instance_count_;
   float dc_level_[2];
   float dc_forgetting_factor_;
   float last_gain_;
+  bool gain_jumpstart_ = false;
+  AudioProcessing::Config::LevelController config_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(LevelController);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_AUDIO_PROCESSING_LEVEL_CONTROLLER_LEVEL_CONTROLLER_H_