Add UMA histograms for WebAudio

third_party/WebKit/Source/modules/webaudio/BiquadProcessor.h

 /*
  * Copyright (C) 2010, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 20 matching lines @@
 #include "platform/audio/AudioDSPKernelProcessor.h"
 #include "platform/audio/Biquad.h"
 #include "wtf/RefPtr.h"
 
 namespace blink {
 
 // BiquadProcessor is an AudioDSPKernelProcessor which uses Biquad objects to implement several common filters.
 
 class BiquadProcessor final : public AudioDSPKernelProcessor {
 public:
+    // This values are used in histograms and should not be renumbered or deleted.
     enum FilterType {
         LowPass = 0,
         HighPass = 1,
         BandPass = 2,
         LowShelf = 3,
         HighShelf = 4,
         Peaking = 5,
         Notch = 6,
         Allpass = 7
     };
@@ skipping 33 matching lines @@
     // so DSP kernels know when to re-compute coefficients
     bool m_filterCoefficientsDirty;
 
     // Set to true if any of the filter parameters are sample-accurate.
     bool m_hasSampleAccurateValues;
 };
 
 } // namespace blink
 
 #endif // BiquadProcessor_h