Fix ALL the include guards.

core/include/fpdfapi/fpdf_page.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 _FPDF_PAGE_
-#define _FPDF_PAGE_
-#ifndef _FPDF_PARSER_
+#ifndef CORE_INCLUDE_FPDFAPI_FPDF_PAGE_H_
+#define CORE_INCLUDE_FPDFAPI_FPDF_PAGE_H_
+
+#include "../fxge/fx_dib.h"
 #include "fpdf_parser.h"
-#endif
-#ifndef _FPDF_RESOURCE_
 #include "fpdf_resource.h"
-#endif
-#ifndef _FX_DIB_H_
-#include "../fxge/fx_dib.h"
-#endif
+
 class CPDF_PageObjects;
 class CPDF_Page;
 class CPDF_Form;
 class CPDF_ParseOptions;
 class CPDF_PageObject;
 class CPDF_PageRenderCache;
 class CPDF_StreamFilter;
 class CPDF_AllStates;
 class CPDF_ContentParser;
 class CPDF_StreamContentParser;
@@ skipping 211 matching lines @@
     void TransformContent(CFX_Matrix& matrix);
 protected:
     void            ProcessImage(CFX_ByteTextBuf& buf, CPDF_ImageObject* pImageObj);
     void            ProcessForm(CFX_ByteTextBuf& buf, FX_LPCBYTE data, FX_DWORD size, CFX_Matrix& matrix);
     CFX_ByteString  RealizeResource(CPDF_Object* pResourceObj, const FX_CHAR* szType);
 private:
     CPDF_Page*      m_pPage;
     CPDF_Document*  m_pDocument;
     CFX_PtrArray    m_pageObjects;
 };
-#endif
+
+#endif  // CORE_INCLUDE_FPDFAPI_FPDF_PAGE_H_