Make down-conversion explicit from CFX_ByteString to CFX_ByteStringC.

core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp

Index: core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp
diff --git a/core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp b/core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp
index 2069a161ea9813c6168b260cf9a23b960b43a8c2..6c1738d5a652a8e30327dcf5ec5cd733ada5771b 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_object_unittest.cpp
@@ -135,7 +135,7 @@ class PDFObjectsTest : public testing::Test {
           return false;
         for (CPDF_Dictionary::const_iterator it = dict1->begin();
              it != dict1->end(); ++it) {
-          if (!Equal(it->second, dict2->GetObjectBy(it->first)))
+          if (!Equal(it->second, dict2->GetObjectBy(it->first.AsByteStringC())))
             return false;
         }
         return true;