Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/graphics/Canvas2DLayerBridge.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 37 matching lines @@
 };
 
 DEFINE_DEBUG_ONLY_GLOBAL(WTF::RefCountedLeakCounter, canvas2DLayerBridgeInstanceCounter, ("Canvas2DLayerBridge"));
 }
 
 namespace WebCore {
 
 static PassRefPtr<SkSurface> createSkSurface(GrContext* gr, const IntSize& size, int msaaSampleCount = 0)
 {
     if (!gr)
-        return 0;
+        return nullptr;
     gr->resetContext();
     SkImageInfo info;
     info.fWidth = size.width();
     info.fHeight = size.height();
     info.fColorType = kPMColor_SkColorType;
     info.fAlphaType = kPremul_SkAlphaType;
     return adoptRef(SkSurface::NewRenderTarget(gr, info,  msaaSampleCount));
 }
 
 PassRefPtr<Canvas2DLayerBridge> Canvas2DLayerBridge::create(const IntSize& size, OpacityMode opacityMode, int msaaSampleCount)
 {
     TRACE_EVENT_INSTANT0("test_gpu", "Canvas2DLayerBridgeCreation");
     OwnPtr<blink::WebGraphicsContext3DProvider> contextProvider = adoptPtr(blink::Platform::current()->createSharedOffscreenGraphicsContext3DProvider());
     if (!contextProvider)
-        return 0;
+        return nullptr;
     RefPtr<SkSurface> surface(createSkSurface(contextProvider->grContext(), size, msaaSampleCount));
     if (!surface)
-        return 0;
+        return nullptr;
     RefPtr<Canvas2DLayerBridge> layerBridge;
     OwnPtr<SkDeferredCanvas> canvas = adoptPtr(SkDeferredCanvas::Create(surface.get()));
     layerBridge = adoptRef(new Canvas2DLayerBridge(contextProvider.release(), canvas.release(), msaaSampleCount, opacityMode));
     return layerBridge.release();
 }
 
 Canvas2DLayerBridge::Canvas2DLayerBridge(PassOwnPtr<blink::WebGraphicsContext3DProvider> contextProvider, PassOwnPtr<SkDeferredCanvas> canvas, int msaaSampleCount, OpacityMode opacityMode)
     : m_canvas(canvas)
     , m_contextProvider(contextProvider)
     , m_msaaSampleCount(msaaSampleCount)
@@ skipping 418 matching lines @@
 Canvas2DLayerBridge::MailboxInfo::MailboxInfo(const MailboxInfo& other) {
     // This copy constructor should only be used for Vector reallocation
     // Assuming 'other' is to be destroyed, we transfer m_image ownership
     // rather than do a refcount dance.
     memcpy(&m_mailbox, &other.m_mailbox, sizeof(m_mailbox));
     m_image = const_cast<MailboxInfo*>(&other)->m_image.release();
     m_status = other.m_status;
 }
 
 }