Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp

Index: core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp
diff --git a/core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp b/core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp
index 6c5339128bf89a25da300019da6b2ea6add54903..af79fd31c1ba7d7efd8bec7a09a0f7bb262db2aa 100644
--- a/core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp
+++ b/core/fpdfapi/fpdf_edit/cpdf_pagecontentgenerator.cpp
@@ -74,12 +74,13 @@ CFX_ByteString CPDF_PageContentGenerator::RealizeResource(
   int idnum = 1;
   while (1) {
     name.Format("FX%c%d", szType[0], idnum);
-    if (!pResList->KeyExist(name)) {
+    if (!pResList->KeyExist(name.AsByteStringC())) {
       break;
     }
     idnum++;
   }
-  pResList->AddReference(name, m_pDocument, pResourceObj->GetObjNum());
+  pResList->AddReference(name.AsByteStringC(), m_pDocument,
+                         pResourceObj->GetObjNum());
   return name;
 }
 void CPDF_PageContentGenerator::ProcessImage(CFX_ByteTextBuf& buf,