Fix a sign mismatch.

TBR=tsepez@chromium.org

Review-Url: https://codereview.chromium.org/1976443002

core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp

diff --git a/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp b/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
index bf1b53c..ae066f9 100644
--- a/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
+++ b/core/fpdfapi/fpdf_parser/cpdf_syntax_parser.cpp
@@ -28,7 +28,7 @@
 
 struct SearchTagRecord {
   CFX_ByteStringC m_bsTag;
-  uint32_t m_Offset;
+  FX_STRSIZE m_Offset;
 };
 
 }  // namespace