Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/audio/HRTFElevation.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
@@ skipping 56 matching lines @@
     DEFINE_STATIC_LOCAL(AudioBusMap, audioBusMap, ());
     DEFINE_STATIC_LOCAL(Mutex, mutex, ());
 
     MutexLocker locker(mutex);
     RefPtr<AudioBus> bus;
     AudioBusMap::iterator iterator = audioBusMap.find(subjectName);
     if (iterator == audioBusMap.end()) {
         RefPtr<AudioBus> concatenatedImpulseResponses(AudioBus::loadPlatformResource(subjectName.utf8().data(), ResponseSampleRate));
         ASSERT(concatenatedImpulseResponses);
         if (!concatenatedImpulseResponses)
-            return 0;
+            return nullptr;
 
         bus = concatenatedImpulseResponses;
         audioBusMap.set(subjectName, bus);
     } else
         bus = iterator->value;
 
     size_t responseLength = bus->length();
     size_t expectedLength = static_cast<size_t>(TotalNumberOfResponses * ResponseFrameSize);
 
     // Check number of channels and length. For now these are fixed and known.
     bool isBusGood = responseLength == expectedLength && bus->numberOfChannels() == 2;
     ASSERT(isBusGood);
     if (!isBusGood)
-        return 0;
+        return nullptr;
 
     return bus;
 }
 #endif
 
 // Takes advantage of the symmetry and creates a composite version of the two measured versions.  For example, we have both azimuth 30 and -30 degrees
 // where the roles of left and right ears are reversed with respect to each other.
 bool HRTFElevation::calculateSymmetricKernelsForAzimuthElevation(int azimuth, int elevation, float sampleRate, const String& subjectName,
                                                                  RefPtr<HRTFKernel>& kernelL, RefPtr<HRTFKernel>& kernelR)
 {
@@ skipping 231 matching lines @@
     double frameDelay2R = m_kernelListR->at(azimuthIndex2)->frameDelay();
 
     // Linearly interpolate delays.
     frameDelayL = (1.0 - azimuthBlend) * frameDelayL + azimuthBlend * frameDelay2L;
     frameDelayR = (1.0 - azimuthBlend) * frameDelayR + azimuthBlend * frameDelay2R;
 }
 
 } // namespace WebCore
 
 #endif // ENABLE(WEB_AUDIO)