Remove CPDF_Object::GetConstString and overrides

core/fpdfapi/fpdf_page/fpdf_page_parser.cpp

Index: core/fpdfapi/fpdf_page/fpdf_page_parser.cpp
diff --git a/core/fpdfapi/fpdf_page/fpdf_page_parser.cpp b/core/fpdfapi/fpdf_page/fpdf_page_parser.cpp
index ba2901df2444780477641449baf9670492f2d4e9..654c9350a9a559173e051a5837026a56ae082b39 100644
--- a/core/fpdfapi/fpdf_page/fpdf_page_parser.cpp
+++ b/core/fpdfapi/fpdf_page/fpdf_page_parser.cpp
@@ -736,9 +736,10 @@ void CPDF_StreamContentParser::Handle_ExecuteXObject() {
     return;
   }
 
-  CFX_ByteStringC type = pXObject->GetDict()
-                             ? pXObject->GetDict()->GetConstStringBy("Subtype")
-                             : CFX_ByteStringC();
+  CFX_ByteString type;
+  if (pXObject->GetDict())
+    type = pXObject->GetDict()->GetStringBy("Subtype");
+
   if (type == "Image") {
     if (m_Options.m_bTextOnly) {
       return;