Remove PageObject's m_Type and add As<Type> functions

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 "core/src/fpdfapi/fpdf_render/render_int.h"
 
 #include "core/include/fpdfapi/fpdf_pageobj.h"
 #include "core/include/fpdfapi/fpdf_render.h"
@@ skipping 300 matching lines @@
   }
   pFont->m_pDocument->GetRenderData()->ReleaseCachedType3(pFont);
   pFont->m_pDocument->GetPageData()->ReleaseFont(pFont->GetFontDict());
 }
 FX_BOOL CPDF_Type3Char::LoadBitmap(CPDF_RenderContext* pContext) {
   if (m_pBitmap || !m_pForm) {
     return TRUE;
   }
   if (m_pForm->GetPageObjectList()->size() == 1 && !m_bColored) {
     auto& pPageObj = m_pForm->GetPageObjectList()->front();
-    if (pPageObj->m_Type == CPDF_PageObject::IMAGE) {
-      CPDF_ImageObject* pImage = static_cast<CPDF_ImageObject*>(pPageObj.get());
-      m_ImageMatrix = pImage->m_Matrix;
-      const CFX_DIBSource* pSource = pImage->m_pImage->LoadDIBSource();
+    if (pPageObj->IsImage()) {
+      const CFX_DIBSource* pSource =
+          pPageObj->AsImage()->m_pImage->LoadDIBSource();
       if (pSource) {
         m_pBitmap = pSource->Clone();
         delete pSource;
       }
       delete m_pForm;
       m_pForm = NULL;
       return TRUE;
     }
   }
   return FALSE;
@@ skipping 447 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);
 }