Upstream foreign fetch tests.

third_party/WebKit/LayoutTests/external/wpt/service-workers/service-worker/resources/foreign-fetch-helpers.js

+// Common helper functions for foreign fetch tests.
+
+// Installs a service worker on a different origin. Both |worker| and |scope|
+// are resolved relative to the /serviceworker/resources/ directory on a

[falken, 2017/02/07 02:10:47]

nit: /service-workers/service-worker/resources/ directory?

[Marijn Kruisselbrink, 2017/02/13 22:00:26]

Done

+// remote origin.
+function install_cross_origin_worker(
+    t, worker, scope, origin = get_host_info().HTTPS_REMOTE_ORIGIN) {
+  return with_iframe(origin + new URL('resources/install-worker-helper.html', location).pathname)
+    .then(frame => new Promise((resolve, reject) => {
+        var channel = new MessageChannel();

[falken, 2017/02/07 02:10:47]

nit: let or const for consistency with fetch_from_different_origin

+        frame.contentWindow.postMessage({worker: worker,
+                                         options: {scope: scope},
+                                         port: channel.port1},

[falken, 2017/02/07 02:10:47]

nit: Is it possible to remove the port property? I think the other side just
gets event.ports[0] directly.

Also, is it possible to just use event.source instead of creating the
MessageChannel? I find MessageChannel to be so verbose and confusing so avoid it
if possible.

[Marijn Kruisselbrink, 2017/02/13 22:00:26]

Yeah, here using event.source directly would indeed work. I often find trying to
use the window global onmessage for replies to be pretty verbose and confusing
(and easy to get wrong), due to all messages from all nested frames, parent
frames and other windows all arriving to the same event listeners. But here it's
not too tricky to work around all that.

+                                        '*', [channel.port1]);
+        channel.port2.onmessage = reply => {
+            if (reply.data == 'success') resolve();
+            else reject(reply.data);
+          };
+      }));
+}
+
+// Performs a fetch from a different origin. By default this performs a fetch
+// from a window on that origin, but if |worker_type| is 'dedicated' or 'shared'
+// the fetch is made from a worker on that origin instead.
+// This uses a window rather than an iframe because an iframe might get blocked
+// by mixed content checks.
+function fetch_from_different_origin(origin, url, worker_type) {
+  var win = open(origin + new URL('resources/foreign-fetch-helper-iframe.html', location).pathname);
+  return new Promise(resolve => {
+        self.addEventListener('message', e => {
+            if (e.source != win) return;
+            resolve();
+          });
+      })
+    .then(() => new Promise((resolve) => {
+        let channel = new MessageChannel();

[falken, 2017/02/07 02:10:47]

const?

[Marijn Kruisselbrink, 2017/02/13 22:00:25]

Done

+        win.postMessage({url: url,
+                         port: channel.port1,
+                         worker: worker_type},
+                        '*', [channel.port1]);
+        channel.port2.onmessage = reply => {
+          win.close();
+          resolve(reply.data);
+        };
+      }));
+}