Fix top crash in blink_http_parsers_fuzzer.

R=bokan@chromium.org

Bug: 830145
Change-Id: I672d9e13aa3118f7c121f6ab8bfef82f46a47ce8
Reviewed-on: https://chromium-review.googlesource.com/c/1327419Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Abhishek Arya <inferno@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606709}

third_party/blink/renderer/platform/network/http_parsers.cc

@@ -381,7 +381,7 @@ ContentTypeOptionsDisposition ParseContentTypeOptionsHeader(
 
   Vector<String> results;
   value.Split(",", results);
-  if (results[0].StripWhiteSpace().LowerASCII() == "nosniff")
+  if (results.size() && results[0].StripWhiteSpace().LowerASCII() == "nosniff")
     return kContentTypeOptionsNosniff;
   return kContentTypeOptionsNone;
 }

third_party/blink/renderer/platform/network/http_parsers_test.cc

@@ -599,6 +599,7 @@ TEST(HTTPParsersTest, ParseContentTypeOptionsTest) {
                {"nosniff , not-nosniff", kContentTypeOptionsNosniff},
                {" nosniff , none", kContentTypeOptionsNosniff},
                {"", kContentTypeOptionsNone},
+               {",", kContentTypeOptionsNone},
                {"none", kContentTypeOptionsNone},
                {"none, nosniff", kContentTypeOptionsNone}};
   for (const auto& test : cases) {