Make CPDF_PageContentGenerator methods take object numbers

core/fpdfapi/page/cpdf_imageobject.cpp

 // Copyright 2016 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/fpdfapi/page/cpdf_imageobject.h"
 
 #include <memory>
 
@@ skipping 61 matching lines @@
     delete m_pImage;
     m_pImage = nullptr;
     m_pImageOwned = false;
     return;
   }
 
   if (!m_pImage)
     return;
 
   CPDF_DocPageData* pPageData = m_pImage->GetDocument()->GetPageData();
-  pPageData->ReleaseImage(m_pImage->GetStream());
+  pPageData->ReleaseImage(m_pImage->GetStream()->GetObjNum());
   m_pImage = nullptr;
 }