Add UMA histograms for WebAudio

third_party/WebKit/Source/platform/audio/Panner.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 28 matching lines @@
 
 class AudioBus;
 class HRTFDatabaseLoader;
 
 // Abstract base class for panning a mono or stereo source.
 
 class PLATFORM_EXPORT Panner {
     USING_FAST_MALLOC(Panner);
     WTF_MAKE_NONCOPYABLE(Panner);
 public:
+    // This values are used in histograms and should not be renumbered or deleted.
     enum {
         PanningModelEqualPower = 0,
         PanningModelHRTF = 1
     };
 
     typedef unsigned PanningModel;
 
     static PassOwnPtr<Panner> create(PanningModel, float sampleRate, HRTFDatabaseLoader*);
 
     virtual ~Panner() { };
 
     virtual void pan(double azimuth, double elevation, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess) = 0;
     virtual void panWithSampleAccurateValues(double* azimuth, double* elevation, const AudioBus* inputBus, AudioBus* outputBus, size_t framesToProcess) = 0;
 
     virtual void reset() = 0;
 
     virtual double tailTime() const = 0;
     virtual double latencyTime() const = 0;
 
 protected:
     Panner(PanningModel model) : m_panningModel(model) { }
 
     PanningModel m_panningModel;
 };
 
 } // namespace blink
 
 #endif // Panner_h