Delay generation of User-Agent header to URLRequestHttpJob and accept custom User-Agent from XHR/Fe…

third_party/WebKit/LayoutTests/http/tests/fetch/resources/fetch-test-helpers.js

 if (self.importScripts) {
   importScripts('/resources/testharness.js');
   importScripts('/serviceworker/resources/test-helpers.js');
   importScripts('/fetch/resources/fetch-test-options.js');
 }
 
 function getContentType(headers) {
   var content_type = '';
   for (var header of headers) {
     if (header[0] == 'content-type')
@@ skipping 69 matching lines @@
   'test \r data', 'test \n data', 'test \0 data',
   'test\r\n data',
   'test\r', 'test\n', 'test\r\n', 'test\0',
   '\0'.repeat(100000), '\r\n'.repeat(50000), 'x'.repeat(100000) + '\0'];
 
 var FORBIDDEN_HEADER_NAMES =
   ['Accept-Charset', 'Accept-Encoding', 'Access-Control-Request-Headers',
    'Access-Control-Request-Method', 'Connection', 'Content-Length',
    'Cookie', 'Cookie2', 'Date', 'DNT', 'Expect', 'Host', 'Keep-Alive',
    'Origin', 'Referer', 'TE', 'Trailer', 'Transfer-Encoding', 'Upgrade',
-   'User-Agent', 'Via', 'Proxy-', 'Sec-', 'Proxy-FooBar', 'Sec-FooBar'];
+   'Via', 'Proxy-', 'Sec-', 'Proxy-FooBar', 'Sec-FooBar'];
 var FORBIDDEN_RESPONSE_HEADER_NAMES =
   ['Set-Cookie', 'Set-Cookie2',
    'set-cookie', 'set-cookie2',
    'set-cOokie', 'set-cOokie2',
    'sEt-cookie', 'sEt-cookie2'];
 var SIMPLE_HEADER_NAMES = ['Accept', 'Accept-Language', 'Content-Language'];
 var CONTENT_TYPE = 'Content-Type';
 var NON_SIMPLE_HEADER_NAMES = ['X-Fetch-Test', 'X-Fetch-Test2'];
 
 var SIMPLE_HEADER_CONTENT_TYPE_VALUES =
@@ skipping 127 matching lines @@
           {referrer: referrer, referrerPolicy: policy, mode: 'cors'});
         return global.fetch(new Request(url, request)).then(res => {
             return res.json();
           }).then(json => {
             assert_equals(json.referrer, expected, 'referrer');
           });
      },
      `referrer test: url = ${url}, referrer = ${referrer}, policy = ${policy}`);
   }
 }