Import //fetch from Web Platform Tests.

third_party/WebKit/LayoutTests/external/wpt/fetch/api/cors/cors-basic.js

+if (this.document === undefined) {
+  importScripts("/resources/testharness.js");
+  importScripts("../resources/utils.js");
+  importScripts("/common/get-host-info.sub.js");
+}
+
+function cors(desc, origin) {
+  var url = origin + dirname(location.pathname);
+  var urlParameters = "?pipe=header(Access-Control-Allow-Origin,*)";
+
+  promise_test(function(test) {
+    return fetch(url + RESOURCES_DIR + "top.txt" + urlParameters, {"mode": "no-cors"} ).then(function(resp) {
+      assert_equals(resp.status, 0, "Opaque filter: status is 0");
+      assert_equals(resp.statusText, "", "Opaque filter: statusText is \"\"");
+      assert_equals(resp.type , "opaque", "Opaque filter: response's type is opaque");
+      return resp.text().then(function(value) {
+        assert_equals(value, "", "Opaque response should have an empty body");
+      });
+    });
+  }, desc + " [no-cors mode]");
+
+  promise_test(function(test) {
+    return promise_rejects(test, new TypeError(), fetch(url + RESOURCES_DIR + "top.txt", {"mode": "cors"}));
+  }, desc + " [server forbid CORS]");
+
+  promise_test(function(test) {
+    return fetch(url + RESOURCES_DIR + "top.txt" + urlParameters, {"mode": "cors"} ).then(function(resp) {
+      assert_equals(resp.status, 200, "Fetch's response's status is 200");
+      assert_equals(resp.type , "cors", "CORS response's type is cors");
+    });
+  }, desc + " [cors mode]");
+}
+
+var host_info = get_host_info();
+
+cors("Same domain different port", host_info.HTTP_ORIGIN_WITH_DIFFERENT_PORT);
+cors("Same domain different protocol different port", host_info.HTTPS_ORIGIN);
+cors("Cross domain basic usage", host_info.HTTP_REMOTE_ORIGIN);
+cors("Cross domain different port", host_info.HTTP_REMOTE_ORIGIN_WITH_DIFFERENT_PORT);
+cors("Cross domain different protocol", host_info.HTTPS_REMOTE_ORIGIN);
+
+done();