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

Index: webrtc/modules/audio_processing/level_controller/peak_level_estimator.h
diff --git a/webrtc/modules/audio_processing/level_controller/peak_level_estimator.h b/webrtc/modules/audio_processing/level_controller/peak_level_estimator.h
index 270bbc3ad0a1e9e7960a36892033b2ea5947d778..4ad2bd371f565004babca1588255aad6ce6377d8 100644
--- a/webrtc/modules/audio_processing/level_controller/peak_level_estimator.h
+++ b/webrtc/modules/audio_processing/level_controller/peak_level_estimator.h
@@ -12,24 +12,26 @@
 #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();
+  explicit PeakLevelEstimator(float initial_peak_level_dbfs);
   ~PeakLevelEstimator();
-  void Initialize();
+  void Initialize(float initial_peak_level_dbfs);
   float Analyze(SignalClassifier::SignalType signal_type,
                 float frame_peak_level);
-
  private:
+  FRIEND_TEST_ALL_PREFIXES(LevelControllerConfig, InitialLevel);

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

Try to get by without these, please. In particular exposing the internals to the
LevelControllerConfig test seems dubious. If they're so tightly coupled, why
have separate classes in the first place?

Adding a unit test for the peak follower is more appropriate (and then you could
test the handling of the initial peak level implicitly).

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

I don't think this is really related to the coupling of classes but rather to
how to test that the specified parameters stick. 

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.

[the sun, 2016/10/06 07:21:13]

Acknowledged.

   float peak_level_;
   int hold_counter_;
   bool initialization_phase_;
 
-  RTC_DISALLOW_COPY_AND_ASSIGN(PeakLevelEstimator);
+  RTC_DISALLOW_IMPLICIT_CONSTRUCTORS(PeakLevelEstimator);
 };
 
 }  // namespace webrtc