Force compiler to deduce src type for checked_cast<dst, src>.

core/fpdfdoc/cpdf_formfield.cpp

 // 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
 
 #include "core/fpdfdoc/cpdf_formfield.h"
 
 #include <set>
 
@@ skipping 664 matching lines @@
 
   CFX_ByteString csStr =
       PDF_EncodeText(csOptLabel.c_str(), csOptLabel.GetLength());
   CPDF_Object* pValue = FPDF_GetFieldAttr(m_pDict, "Opt");
   CPDF_Array* pOpt = ToArray(pValue);
   if (!pOpt) {
     pOpt = new CPDF_Array;
     m_pDict->SetFor("Opt", pOpt);
   }
 
-  int iCount = pdfium::base::checked_cast<int, size_t>(pOpt->GetCount());
+  int iCount = pdfium::base::checked_cast<int>(pOpt->GetCount());
   if (index >= iCount) {
     pOpt->AddString(csStr);
     index = iCount;
   } else {
     CPDF_String* pString = new CPDF_String(csStr, false);
     pOpt->InsertAt(index, pString);
   }
 
   if (bNotify)
     NotifyListOrComboBoxAfterChange();
@@ skipping 293 matching lines @@
     case ListBox:
       NotifyAfterSelectionChange();
       break;
     case ComboBox:
       NotifyAfterValueChange();
       break;
     default:
       break;
   }
 }