Check the mime type of cross-origin CSS fetched via the Service Worker.

third_party/WebKit/LayoutTests/http/tests/serviceworker/resources/fetch-request-css-cross-origin-mime-check-worker.js

+importScripts('../../resources/get-host-info.js');
+importScripts('test-helpers.js');
+
+self.addEventListener('fetch', function(event) {
+    if (event.request.url.indexOf('dummy.css') != -1) {
+      event.respondWith(fetch(
+          get_host_info()['HTTP_REMOTE_ORIGIN'] + base_path() +
+          'fetch-request-css-cross-origin-mime-check-secret.html',
+          {mode: 'no-cors'}));
+    }
+  });