Remove even more const casting from core.

core/fpdfdoc/include/fpdf_doc.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_FPDFDOC_INCLUDE_FPDF_DOC_H_
 #define CORE_FPDFDOC_INCLUDE_FPDF_DOC_H_
 
 #include <map>
@@ skipping 515 matching lines @@
   void SetFormNotify(IPDF_FormNotify* pNotify);
   FX_BOOL HasXFAForm() const;
   void FixPageFields(const CPDF_Page* pPage);
 
  protected:
   static FX_BOOL s_bUpdateAP;
 
   void LoadField(CPDF_Dictionary* pFieldDict, int nLevel = 0);
   CPDF_Object* GetFieldAttr(CPDF_Dictionary* pFieldDict, const FX_CHAR* name);
   CPDF_FormField* AddTerminalField(CPDF_Dictionary* pFieldDict);
-  CPDF_FormControl* AddControl(const CPDF_FormField* pField,
+  CPDF_FormControl* AddControl(CPDF_FormField* pField,
                                CPDF_Dictionary* pWidgetDict);
   void FDF_ImportField(CPDF_Dictionary* pField,
                        const CFX_WideString& parent_name,
                        FX_BOOL bNotify = FALSE,
                        int nLevel = 0);
   FX_BOOL ValidateFieldName(CFX_WideString& csNewFieldName,
                             int iType,
                             const CPDF_FormField* pExcludedField,
                             const CPDF_FormControl* pExcludedControl);
   int CompareFieldName(const CFX_WideString& name1,
@@ skipping 387 matching lines @@
   CFX_WideString GetCaption(const CFX_ByteString& csEntry) const;
   CPDF_Stream* GetIcon(const CFX_ByteString& csEntry) const;
 
   CPDF_Dictionary* const m_pDict;
 };
 
 CPDF_Stream* FPDFDOC_GetAnnotAP(CPDF_Dictionary* pAnnotDict,
                                 CPDF_Annot::AppearanceMode mode);
 
 #endif  // CORE_FPDFDOC_INCLUDE_FPDF_DOC_H_