Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/modules/webaudio/BiquadProcessor.cpp

 /*
  * 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 17 matching lines @@
 
 #include "modules/webaudio/BiquadProcessor.h"
 
 #include "modules/webaudio/BiquadDSPKernel.h"
 
 namespace WebCore {
 
 BiquadProcessor::BiquadProcessor(AudioContext* context, float sampleRate, size_t numberOfChannels, bool autoInitialize)
     : AudioDSPKernelProcessor(sampleRate, numberOfChannels)
     , m_type(LowPass)
-    , m_parameter1(0)
-    , m_parameter2(0)
-    , m_parameter3(0)
-    , m_parameter4(0)
+    , m_parameter1(nullptr)
+    , m_parameter2(nullptr)
+    , m_parameter3(nullptr)
+    , m_parameter4(nullptr)
     , m_filterCoefficientsDirty(true)
     , m_hasSampleAccurateValues(false)
 {
     double nyquist = 0.5 * this->sampleRate();
 
     // Create parameters for BiquadFilterNode.
     m_parameter1 = AudioParam::create(context, "frequency", 350.0, 10.0, nyquist);
     m_parameter2 = AudioParam::create(context, "Q", 1, 0.0001, 1000.0);
     m_parameter3 = AudioParam::create(context, "gain", 0.0, -40, 40);
     m_parameter4 = AudioParam::create(context, "detune", 0.0, -4800, 4800);
@@ skipping 77 matching lines @@
     // thread on the main kernels.
 
     OwnPtr<BiquadDSPKernel> responseKernel = adoptPtr(new BiquadDSPKernel(this));
 
     responseKernel->getFrequencyResponse(nFrequencies, frequencyHz, magResponse, phaseResponse);
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)