Get rid of NULLs in core/

core/fpdfapi/fpdf_font/cpdf_simplefont.h

 // Copyright 2016 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef CORE_FPDFAPI_FPDF_FONT_CPDF_SIMPLEFONT_H_
 #define CORE_FPDFAPI_FPDF_FONT_CPDF_SIMPLEFONT_H_
 
 #include "core/fpdfapi/fpdf_font/include/cpdf_font.h"
 #include "core/fpdfapi/fpdf_font/include/cpdf_fontencoding.h"
 #include "core/fxcrt/include/fx_string.h"
 #include "core/fxcrt/include/fx_system.h"
 
 class CPDF_SimpleFont : public CPDF_Font {
  public:
   CPDF_SimpleFont();
   virtual ~CPDF_SimpleFont();
 
   // CPDF_Font:
   int GetCharWidthF(uint32_t charcode, int level = 0) override;
   FX_RECT GetCharBBox(uint32_t charcode, int level = 0) override;
-  int GlyphFromCharCode(uint32_t charcode, FX_BOOL* pVertGlyph = NULL) override;
+  int GlyphFromCharCode(uint32_t charcode,
+                        FX_BOOL* pVertGlyph = nullptr) override;
   FX_BOOL IsUnicodeCompatible() const override;
   CFX_WideString UnicodeFromCharCode(uint32_t charcode) const override;
   uint32_t CharCodeFromUnicode(FX_WCHAR Unicode) const override;
 
   CPDF_FontEncoding* GetEncoding() { return &m_Encoding; }
 
  protected:
   virtual void LoadGlyphMap() = 0;
 
   FX_BOOL LoadCommon();
   void LoadSubstFont();
   void LoadFaceMetrics();
   void LoadCharMetrics(int charcode);
 
   CPDF_FontEncoding m_Encoding;
   uint16_t m_GlyphIndex[256];
   uint16_t m_ExtGID[256];
   CFX_ByteString* m_pCharNames;
   int m_BaseEncoding;
   uint16_t m_CharWidth[256];
   FX_SMALL_RECT m_CharBBox[256];
   FX_BOOL m_bUseFontWidth;
 };
 
 #endif  // CORE_FPDFAPI_FPDF_FONT_CPDF_SIMPLEFONT_H_