Avoid adding invalid headers in AddHeaderFromString

net/http/http_content_disposition.cc

Index: net/http/http_content_disposition.cc
diff --git a/net/http/http_content_disposition.cc b/net/http/http_content_disposition.cc
index 3f7d6b5f8a13b594b5015bc1b123cae80fc2527b..eb59b6d232bc3ea1eccb761947a2916a5c2f69e0 100644
--- a/net/http/http_content_disposition.cc
+++ b/net/http/http_content_disposition.cc
@@ -6,6 +6,7 @@
 
 #include "base/base64.h"
 #include "base/logging.h"
+#include "base/strings/string_piece.h"
 #include "base/strings/string_tokenizer.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
@@ -353,8 +354,11 @@ std::string::const_iterator HttpContentDisposition::ConsumeDispositionType(
   // If the disposition-type isn't a valid token the then the
   // Content-Disposition header is malformed, and we treat the first bytes as
   // a parameter rather than a disposition-type.
-  if (!HttpUtil::IsToken(type_begin, type_end))
+  if (type_begin == type_end ||
+      !HttpUtil::IsToken(
+          base::StringPiece(&*type_begin, type_end - type_begin))) {
     return begin;
+  }
 
   parse_result_flags_ |= HAS_DISPOSITION_TYPE;