Remove header files that only have includes.

fpdfsdk/include/formfiller/FFL_IFormFiller.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_INCLUDE_FORMFILLER_FFL_IFORMFILLER_H_
 #define FPDFSDK_INCLUDE_FORMFILLER_FFL_IFORMFILLER_H_
 
 #include <map>
 
-#include "FormFiller.h"
+#include "fpdfsdk/include/fsdk_define.h"
+#include "fpdfsdk/include/pdfwindow/PWL_Edit.h"
 
 class CFFL_FormFiller;
 class CFFL_PrivateData;
+class CPDFDoc_Environment;
+class CPDFSDK_Annot;
+class CPDFSDK_PageView;
+class CPDFSDK_Widget;
 
 class CFFL_IFormFiller : public IPWL_Filler_Notify {
  public:
   explicit CFFL_IFormFiller(CPDFDoc_Environment* pApp);
   ~CFFL_IFormFiller() override;
 
   virtual FX_BOOL Annot_HitTest(CPDFSDK_PageView* pPageView,
                                 CPDFSDK_Annot* pAnnot,
                                 CPDF_Point point);
   virtual FX_RECT GetViewBBox(CPDFSDK_PageView* pPageView,
@@ skipping 115 matching lines @@
 
 class CFFL_PrivateData {
  public:
   CPDFSDK_Widget* pWidget;
   CPDFSDK_PageView* pPageView;
   int nWidgetAge;
   int nValueAge;
 };
 
 #endif  // FPDFSDK_INCLUDE_FORMFILLER_FFL_IFORMFILLER_H_