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ui/webui/resources/js/webui_listener_tracker.js

Index: ui/webui/resources/js/webui_listener_tracker.js
diff --git a/ui/webui/resources/js/webui_listener_tracker.js b/ui/webui/resources/js/webui_listener_tracker.js
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+// Copyright 2017 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 Class that manages the addition and removal of WebUI
+ * listeners.
+ */
+
+/**
+ * Create a WebUIListenerTracker to track a set of Web UI listeners.
+ * @constructor
+ */
+function WebUIListenerTracker() {
+  /**
+   * The Web UI listeners being tracked.
+   * @private {!Array<!WebUIListener>}
+   */
+  this.listeners_ = [];
+}
+
+WebUIListenerTracker.prototype = {
+  /**
+   * Adds a WebUI listener to the array of listeners being tracked, which
+   * will be removed when removeAll() is called.
+   * Do not use this method if the listener will be removed manually.
+   * @param {string} eventName The event to listen to.
+   * @param {!Function} callback The callback to run when the event is fired.
+   */
+  add: function(eventName, callback) {
+    this.listeners_.push(cr.addWebUIListener(eventName, callback));
+  },
+
+  /**
+   * Removes all Web UI listeners that are currently being tracked.
+   */
+  removeAll: function() {
+    while (this.listeners_.length > 0) {
+      cr.removeWebUIListener(this.listeners_.pop());
+    }
+  },
+};