Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/graphics/DecodingImageGenerator.cpp

 /*
  * Copyright (C) 2012 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 34 matching lines @@
 
 DecodingImageGenerator::~DecodingImageGenerator()
 {
 }
 
 SkData* DecodingImageGenerator::refEncodedData()
 {
     // FIXME: If the image has been clipped or scaled, do not return the original
     // encoded data, since on playback it will not be known how the clipping/scaling
     // was done.
-    RefPtr<SharedBuffer> buffer = 0;
+    RefPtr<SharedBuffer> buffer = nullptr;
     bool allDataReceived = false;
     m_frameGenerator->copyData(&buffer, &allDataReceived);
     if (buffer && allDataReceived) {
         return SkData::NewWithCopy(buffer->data(), buffer->size());
     }
     return 0;
 }
 
 bool DecodingImageGenerator::getInfo(SkImageInfo* info)
 {
@@ skipping 11 matching lines @@
     ASSERT(info.fHeight == m_imageInfo.fHeight);
     ASSERT(info.fColorType == m_imageInfo.fColorType);
     ASSERT(info.fAlphaType == m_imageInfo.fAlphaType);
     PlatformInstrumentation::willDecodeLazyPixelRef(m_generationId);
     bool decoded = m_frameGenerator->decodeAndScale(m_imageInfo, m_frameIndex, pixels, rowBytes);
     PlatformInstrumentation::didDecodeLazyPixelRef(m_generationId);
     return decoded;
 }
 
 } // namespace blink