Rename fpdfsdk/fpdfxfa files to match contents

fpdfsdk/fpdfxfa/cpdfxfa_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 FPDFSDK_FPDFXFA_FPDFXFA_PAGE_H_
-#define FPDFSDK_FPDFXFA_FPDFXFA_PAGE_H_
+#ifndef FPDFSDK_FPDFXFA_CPDFXFA_PAGE_H_
+#define FPDFSDK_FPDFXFA_CPDFXFA_PAGE_H_
 
 #include <memory>
 
 #include "core/fxcrt/fx_system.h"
 
 class CFX_Matrix;
 class CPDFXFA_Document;
 class CPDF_Dictionary;
 class CPDF_Page;
 class CXFA_FFPageView;
@@ skipping 56 matching lines @@
   FX_BOOL LoadXFAPageView();
 
  private:
   std::unique_ptr<CPDF_Page> m_pPDFPage;
   CXFA_FFPageView* m_pXFAPageView;
   CPDFXFA_Document* const m_pDocument;
   const int m_iPageIndex;
   int m_iRef;
 };
 
-#endif  // FPDFSDK_FPDFXFA_FPDFXFA_PAGE_H_
+#endif  // FPDFSDK_FPDFXFA_CPDFXFA_PAGE_H_