Get rid of most instance of 'foo == NULL'

core/include/fpdfapi/fpdf_resource.h

 // Copyright 2014 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_INCLUDE_FPDFAPI_FPDF_RESOURCE_H_
 #define CORE_INCLUDE_FPDFAPI_FPDF_RESOURCE_H_
 
 #include <map>
@@ skipping 587 matching lines @@
   FX_DWORD m_dwStdConversion;
 };
 class CPDF_Color {
  public:
   CPDF_Color() : m_pCS(NULL), m_pBuffer(NULL) {}
 
   CPDF_Color(int family);
 
   ~CPDF_Color();
 
-  FX_BOOL IsNull() const { return m_pBuffer == NULL; }
+  FX_BOOL IsNull() const { return !m_pBuffer; }
 
   FX_BOOL IsEqual(const CPDF_Color& other) const;
 
   FX_BOOL IsPattern() const {
     return m_pCS && m_pCS->GetFamily() == PDFCS_PATTERN;
   }
 
   void Copy(const CPDF_Color* pSrc);
 
   void SetColorSpace(CPDF_ColorSpace* pCS);
@@ skipping 233 matching lines @@
 
   FX_BOOL m_bInterpolate;
 
   CPDF_Document* m_pDocument;
 
   CPDF_Dictionary* m_pOC;
   CPDF_Dictionary* InitJPEG(uint8_t* pData, FX_DWORD size);
 };
 
 #endif  // CORE_INCLUDE_FPDFAPI_FPDF_RESOURCE_H_