commit 85c5c356b9409cd92220519aab3ba88b5edd16e6
Author: Hans Wennborg <hans@chromium.org>
Date:   Mon Oct 23 08:54:35 2017 -0700

    Fix Win/Clang -Wsign-compare warning
    
    enums are backed by signed integers by default on Windows, and Clang
    (after r316268) would warn about comparing 'code', which is signed, with
    sizeof(..) which is unsigned.
    
    Bug: 777363

diff --git a/third_party/expat/files/lib/xmlparse.c b/third_party/expat/files/lib/xmlparse.c
index 6d8dc1e33591..6ff81029ce29 100644
--- a/third_party/expat/files/lib/xmlparse.c
+++ b/third_party/expat/files/lib/xmlparse.c
@@ -2426,7 +2426,7 @@ XML_ErrorString(enum XML_Error code)
     XML_L("reserved prefix (xmlns) must not be declared or undeclared"),
     XML_L("prefix must not be bound to one of the reserved namespace names")
   };
-  if (code > 0 && code < sizeof(message)/sizeof(message[0]))
+  if (code > 0 && (size_t)code < sizeof(message)/sizeof(message[0]))
     return message[code];
   return NULL;
 }