Properly ref-count CFGAS_GEFont with CFX_RetainPtr.

xfa/fgas/layout/fgas_unicode.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 XFA_FGAS_LAYOUT_FGAS_UNICODE_H_
 #define XFA_FGAS_LAYOUT_FGAS_UNICODE_H_
 
 #include "xfa/fgas/crt/fgas_utils.h"
 #include "xfa/fgas/font/cfgas_fontmgr.h"
 
 struct FX_TPO {
   int32_t index;
   int32_t pos;
 };
 typedef CFX_MassArrayTemplate<FX_TPO> CFX_TPOArray;
 
 void FX_TEXTLAYOUT_PieceSort(CFX_TPOArray& tpos, int32_t iStart, int32_t iEnd);
 
-typedef bool (*FX_AdjustCharDisplayPos)(FX_WCHAR wch,
-                                        bool bMBCSCode,
-                                        CFGAS_GEFont* pFont,
-                                        FX_FLOAT fFontSize,
-                                        bool bVertical,
-                                        CFX_PointF& ptOffset);
+typedef bool (*FX_AdjustCharDisplayPos)(
+    FX_WCHAR wch,
+    bool bMBCSCode,
+    const CFX_RetainPtr<CFGAS_GEFont>& pFont,
+    FX_FLOAT fFontSize,
+    bool bVertical,
+    CFX_PointF& ptOffset);
 
 #endif  // XFA_FGAS_LAYOUT_FGAS_UNICODE_H_