[ServiceWorker] Set FetchRequestMode and handle wasFetchedViaServiceWorker.

LayoutTests/http/tests/serviceworker/resources/fetch-request-xhr-iframe.html

 <script src="../../resources/testharness.js"></script>
 <script src="test-helpers.js?pipe=sub"></script>
 <script>
+var host_info = get_host_info();
+
 function get_boundary(headers) {
   var reg = new RegExp('multipart\/form-data; boundary=(.*)');
   for (var i = 0; i < headers.length; ++i) {
     if (headers[i][0] != 'content-type') {
       continue;
     }
     var regResult = reg.exec(headers[i][1]);
     if (!regResult) {
       continue;
     }
@@ skipping 13 matching lines @@
                     fileEntry.file(function(file) { resolve(file); });
                   };
                   var blob = new Blob([data], {type: 'text/plain'});
                   fileWriter.write(blob);
                 });
             }, function(e) { reject(e); });
         }, function(e) { reject(e); });
     });
 }
 
-function xhr_send(method, data) {
+function xhr_send(url_base, method, data, with_credentials) {
   return new Promise(function(resolve, reject) {
       var xhr = new XMLHttpRequest();
       xhr.onload = function() {
         resolve(JSON.parse(xhr.response));
       };
       xhr.onerror = function() {
         reject('XHR should succeed.');
       };
       xhr.responseType = 'text';
-      xhr.open(method, './dummy?test', true);
+      if (with_credentials) {
+        xhr.withCredentials = true;
+      }
+      xhr.open(method, url_base + '/dummy?test', true);
       xhr.send(data);
     });
 }
 
 function string_test() {
-  return xhr_send('POST', 'test string')
+  return xhr_send(host_info['HTTP_ORIGIN'], 'POST', 'test string', false)
     .then(function(response) {
         assert_equals(response.method, 'POST');
         assert_equals(response.body, 'test string');
       });
 }
 
 function blob_test() {
-  return xhr_send('POST', new Blob(['test blob']))
+  return xhr_send(host_info['HTTP_ORIGIN'], 'POST', new Blob(['test blob']),
+                  false)
     .then(function(response) {
         assert_equals(response.method, 'POST');
         assert_equals(response.body, 'test blob');
       });
 }
 
 function custom_method_test() {
-  return xhr_send('XXX', 'test string xxx')
+  return xhr_send(host_info['HTTP_ORIGIN'], 'XXX', 'test string xxx', false)
     .then(function(response){
         assert_equals(response.method, 'XXX');
         assert_equals(response.body, 'test string xxx');
       });
 }
 
 function form_data_test() {
   return create_file_system_file('fsfile.txt', 'fs file content')
     .then(function(file_system_file) {
         var formData = new FormData();
         formData.append('sample string', '1234567890');
         formData.append('sample blob', new Blob(['blob content']));
         formData.append('sample file', new File(['file content'], 'file.dat'));
         formData.append('sample fs file', file_system_file);
-        return xhr_send('POST', formData);
+        return xhr_send(host_info['HTTP_ORIGIN'], 'POST', formData, false);
       })
     .then(function(response) {
         assert_equals(response.method, 'POST');
         var boundary = get_boundary(response.headers);
         var expected_body =
           '--' + boundary + '\r\n' +
           'Content-Disposition: form-data; name="sample string"\r\n' +
           '\r\n' +
           '1234567890\r\n' +
           '--' + boundary + '\r\n' +
@@ skipping 12 matching lines @@
           'Content-Disposition: form-data; name="sample fs file"; ' +
           'filename="fsfile.txt"\r\n' +
           'Content-Type: text/plain\r\n' +
           '\r\n' +
           'fs file content\r\n' +
           '--' + boundary + '--\r\n';
         assert_equals(response.body, expected_body);
       });
 }
 
+function mode_test() {
+  return xhr_send(host_info['HTTP_ORIGIN'], 'GET', '', false)
+    .then(function(response){
+        assert_equals(response.mode, 'cors');
+        return xhr_send(host_info['HTTP_ORIGIN'], 'GET', '', true);
+      })
+    .then(function(response){
+        assert_equals(response.mode, 'cors');
+        return xhr_send(host_info['HTTP_REMOTE_ORIGIN'], 'GET', '', false);
+      })
+    .then(function(response){
+        assert_equals(response.mode, 'cors');
+        return xhr_send(host_info['HTTP_REMOTE_ORIGIN'], 'GET', '', true);
+      })
+    .then(function(response){
+        assert_equals(response.mode, 'cors');
+      });
+}
+
 window.addEventListener('message', function(evt) {
     var port = evt.ports[0];
     string_test()
       .then(blob_test)
       .then(custom_method_test)
       .then(form_data_test)
+      .then(mode_test)
       .then(function() { port.postMessage({results: 'finish'}); })
       .catch(function(e) { port.postMessage({results: 'failure:' + e}); });
   });
 </script>