Implement the events for Background Fetch

third_party/WebKit/LayoutTests/http/tests/background_fetch/resources/background-fetch-click-event-worker.js

+'use strict';
+
+importScripts('/resources/testharness.js');
+
+test(function() {
+  assert_own_property(self, 'BackgroundFetchClickEvent');
+
+  // The `tag` and `state` are required in the BackgroundFetchClickEventInit.
+  assert_throws(null, () => new BackgroundFetchClickEvent('BackgroundFetchClickEvent'));
+  assert_throws(null, () => new BackgroundFetchClickEvent('BackgroundFetchClickEvent', {}));
+  assert_throws(null, () => new BackgroundFetchClickEvent('BackgroundFetchClickEvent', { tag: 'foo' }));
+  assert_throws(null, () => new BackgroundFetchClickEvent('BackgroundFetchClickEvent', { tag: 'foo', state: 'foo' }));
+
+  // The `state` must be one of { pending, succeeded, failed }. This should not throw.
+  for (let state of ['pending', 'succeeded', 'failed'])
+    new BackgroundFetchClickEvent('BackgroundFetchClickEvent', { tag: 'foo', state });

[harkness, 2017/03/09 19:41:15]

Are there tag formats that we won't allow?

[Peter Beverloo, 2017/03/10 00:42:50]

No, it follows the semantics of a DOMString.

+
+  const event = new BackgroundFetchClickEvent('BackgroundFetchClickEvent', {
+    tag: 'my-tag',
+    state: 'succeeded'
+  });
+
+  assert_equals(event.type, 'BackgroundFetchClickEvent');

[harkness, 2017/03/09 19:41:15]

Why not check these in the for loop above for each state and remove this one?

[Peter Beverloo, 2017/03/10 00:42:50]

Logically line 15/16 are testing that the allowed values don't fail, this is
testing that the event has the right properties (type, cancelable, bubbling and
so on). I don't feel strongly.

+  assert_equals(event.cancelable, false);
+  assert_equals(event.bubbles, false);
+  assert_equals(event.tag, 'my-tag');
+  assert_equals(event.state, 'succeeded');
+
+  assert_inherits(event, 'waitUntil');
+
+}, 'Verifies that the BackgroundFetchClickEvent can be constructed.');