Use nullptr_t for RefPtr, PassRefPtr and RawPtr.

Source/platform/fonts/android/FontCacheAndroid.cpp

 /*
  * Copyright (c) 2011 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:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 54 matching lines @@
     SkString skiaFamilyName;
     if (!SkGetFallbackFamilyNameForChar(c, locale, &skiaFamilyName) || skiaFamilyName.isEmpty())
         return AtomicString();
     return skiaFamilyName.c_str();
 }
 
 PassRefPtr<SimpleFontData> FontCache::platformFallbackForCharacter(const FontDescription& fontDescription, UChar32 c, const SimpleFontData*)
 {
     AtomicString familyName = getFamilyNameForCharacter(c, fontDescription.script());
     if (familyName.isEmpty())
-        return 0;
+        return nullptr;
     return fontDataFromFontPlatformData(getFontPlatformData(fontDescription, familyName), DoNotRetain);
 }
 
 // static
 AtomicString FontCache::getGenericFamilyNameForScript(const AtomicString& familyName, UScriptCode script)
 {
     // This is a hack to use the preferred font for CJK scripts.
     // FIXME: Use new Skia API once Android system supports per-family and per-script fallback fonts.
     UChar32 examplerChar;
     switch (script) {
     case USCRIPT_SIMPLIFIED_HAN:
     case USCRIPT_TRADITIONAL_HAN:
     case USCRIPT_KATAKANA_OR_HIRAGANA:
         examplerChar = 0x4E00; // A common character in Japanese and Chinese.
         break;
     case USCRIPT_HANGUL:
         examplerChar = 0xAC00;
         break;
     default:
         // For other scripts, use the default generic family mapping logic.
         return familyName;
     }
 
     return getFamilyNameForCharacter(examplerChar, script);
 }
 
 } // namespace WebCore