Add FakeChromeEvent

chrome/test/data/webui/fake_chrome_event.js

Index: chrome/test/data/webui/fake_chrome_event.js
diff --git a/chrome/test/data/webui/fake_chrome_event.js b/chrome/test/data/webui/fake_chrome_event.js
new file mode 100644
index 0000000000000000000000000000000000000000..27a18712a2e297280fab575663ad09dbf489f3db
--- /dev/null
+++ b/chrome/test/data/webui/fake_chrome_event.js
@@ -0,0 +1,39 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+/**
+ * @fileoverview Fake implementations of ChromeEvent.
+ */
+
+/**
+ * @constructor
+ * @extends {ChromeEvent}
+ */
+function FakeChromeEvent() {
+  /** @type {!Array<!Function>} */
+  this.listeners_ = [];
+}
+
+FakeChromeEvent.prototype = {
+  /** @param {Function} listener */
+  addListener: function(listener) {
+    this.listeners_.push(listener);
+  },
+
+  /** @param {Function} listener */
+  removeListener: function(listener) {
+    var index = this.listeners_.indexOf(listener);

[dpapad, 2015/12/16 21:18:07]

Can you use a native Javascript Set instead of an array? I used it for the first
time in Chromium's codebase at https://codereview.chromium.org/1518203003. This
way you don't need to do linear searching (indexOf).

[stevenjb, 2015/12/16 22:20:57]

Done.

+    if (index < 0) {
+      console.error('removeListener: not found');
+      return;
+    }
+    this.listeners_.slice(index, 1);
+  },
+
+  /** @param {...} args */
+  callListeners: function(...args) {
+    for (var l of this.listeners_)
+      l.apply(null, args);
+  }
+};