Leave out empty-valued Access-Control-Request-Headers: on preflights.

third_party/WebKit/LayoutTests/http/tests/fetch/resources/thorough-util.js

 var SCOPE = BASE_ORIGIN +
   '/fetch/resources/thorough-iframe.html?' + TEST_OPTIONS;
 var IFRAME_ORIGIN = BASE_ORIGIN;
 var BASE_URL = BASE_ORIGIN +
   '/serviceworker/resources/fetch-access-control.php?';
 var OTHER_BASE_URL = OTHER_ORIGIN +
   '/serviceworker/resources/fetch-access-control.php?';
 var BASE_URL_WITH_USERNAME = BASE_URL.replace('://', '://user@');
 var OTHER_BASE_URL_WITH_USERNAME = OTHER_BASE_URL.replace('://', '://user@');
 var BASE_URL_WITH_PASSWORD = BASE_URL.replace('://', '://user:pass@');
@@ skipping 301 matching lines @@
   }
   if (params['headers'] === 'CUSTOM') {
     init['headers'] = {'X-ServiceWorker-Test': 'test'};
   } else if (params['headers'] === 'CUSTOM2') {
     init['headers'] = [['X-ServiceWorker-Test', 'test2'],
                        ['X-ServiceWorker-ua', 'test4'],
                        ['X-ServiceWorker-V', 'test6'],
                        ['X-ServiceWorker-s', 'test1'],
                        ['X-ServiceWorker-Test', 'test3'],
                        ['X-ServiceWorker-U', 'test5']];
+  } else if (params['headers'] === 'SAFE') {
+    init['headers'] = [['Accept', '*/*'],
+                       ['Accept-Language', 'en-us,de'],
+                       ['Content-Language', 'en-us'],
+                       ['Content-Type', 'text/plain'],
+                       ['Save-data', 'on']];
   } else if (params['headers'] === '{}') {
     init['headers'] = {};
   }
   return init;
 }
 
 function headersToArray(headers) {
   var ret = [];
 
   // Workaround for Firefox. iterable is not implemented yet.
@@ skipping 106 matching lines @@
 
 function executeTests(test_targets) {
   for (var i = 0; i < test_targets.length; ++i) {
     promise_test(
       function(counter, t) {
         return executeTest(test_targets[counter]);
       }.bind(this, i),
       "executeTest-" + i);
   }
 }