Extern in .cpp file is a code smell, part 2.

core/src/fpdfapi/fpdf_render/fpdf_render_text.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 "../../../include/fxge/fx_ge.h"
 #include "../../../include/fpdfapi/fpdf_render.h"
 #include "../../../include/fpdfapi/fpdf_pageobj.h"
 #include "../fpdf_page/pageint.h"
 #include "render_int.h"
-extern FX_BOOL IsAvailableMatrix(const CFX_AffineMatrix& matrix);
+
 CPDF_Type3Cache::~CPDF_Type3Cache() {
   for (const auto& pair : m_SizeMap) {
     delete pair.second;
   }
   m_SizeMap.clear();
 }
 CFX_GlyphBitmap* CPDF_Type3Cache::LoadGlyph(FX_DWORD charcode,
                                             const CFX_AffineMatrix* pMatrix,
                                             FX_FLOAT retinaScaleX,
                                             FX_FLOAT retinaScaleY) {
@@ skipping 765 matching lines @@
     ProcessPath(&path, pObj2Device);
   }
 }
 
 CFX_PathData* CPDF_Font::LoadGlyphPath(FX_DWORD charcode, int dest_width) {
   int glyph_index = GlyphFromCharCode(charcode);
   if (!m_Font.GetFace())
     return nullptr;
   return m_Font.LoadGlyphPath(glyph_index, dest_width);
 }