| Index: chrome/browser/resources/touch_ntp/eventtracker.js
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| diff --git a/chrome/browser/resources/touch_ntp/eventtracker.js b/chrome/browser/resources/touch_ntp/eventtracker.js
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| new file mode 100644
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| index 0000000000000000000000000000000000000000..bb76f5e920b772f95d80302e1e41fefb1ae3a89a
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| --- /dev/null
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| +++ b/chrome/browser/resources/touch_ntp/eventtracker.js
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| @@ -0,0 +1,99 @@
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| +// Copyright (c) 2011 The Chromium Authors. All rights reserved.
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| +// Use of this source code is governed by a BSD-style license that can be
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| +// found in the LICENSE file.
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| +
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| +/** @fileoverview EventTracker is a simple class that manages the addition and
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| + * removal of DOM event listeners. In particular, it keeps track of all
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| + * listeners that have been added and makes it easy to remove some or all of
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| + * them without requiring all the information again. This is particularly
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| + * handy when the listener is a generated function such as a lambda or the
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| + * result of calling Function.bind. The goal of this class is to make it
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| + * easier to avoid memory leaks caused by DOM<->JS cycles - removing event
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| + * listeners breakes the DOM->JS part of the cycle.
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| + */
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| +
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| +// Use an anonymous function to enable strict mode just for this file (which
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| +// will be concatenated with other files when embedded in Chrome)
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| +var EventTracker = (function() {
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| + 'use strict';
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| +
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| + /**
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| + * Create an EventTracker to track a set of events.
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| + * EventTracker instances are typically tied 1:1 with other objects or
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| + * DOM elements whose listeners should be removed when the object is disposed
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| + * or the corresponding elements are removed from the DOM.
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| + * @constructor
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| + */
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| + function EventTracker() {
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| + /**
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| + * @type {Array.<EventTracker.Entry>}
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| + * @private
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| + */
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| + this.listeners_ = [];
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| + }
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| +
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| + /**
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| + * The type of the internal tracking entry.
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| + * @typedef {{node: !Node,
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| + * eventType: string,
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| + * listener: Function,
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| + * capture: boolean}}
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| + */
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| + EventTracker.Entry;
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| +
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| + EventTracker.prototype = {
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| + /**
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| + * Add an event listener - replacement for Node.addEventListener.
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| + * @param {!Node} node The DOM node to add a listener to.
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| + * @param {string} eventType The type of event to subscribe to.
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| + * @param {Function} listener The listener to add.
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| + * @param {boolean} capture Whether to invoke during the capture phase.
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| + */
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| + add: function(node, eventType, listener, capture) {
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| + var h = {
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| + node: node,
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| + eventType: eventType,
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| + listener: listener,
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| + capture: capture
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| + };
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| + this.listeners_.push(h);
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| + node.addEventListener(eventType, listener, capture);
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| + },
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| +
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| + /**
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| + * Remove any specified event listeners added with this EventTracker.
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| + * @param {!Node} node The DOM node to remove a listener from.
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| + * @param {string} eventType The type of event to remove.
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| + */
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| + remove: function(node, eventType) {
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| + this.listeners_ = this.listeners_.filter(function(h) {
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| + if (h.node == node && h.eventType == eventType) {
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| + EventTracker.removeEventListener_(h);
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| + return false;
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| + }
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| + return true;
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| + });
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| + },
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| +
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| + /**
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| + * Remove all event listeners added with this EventTracker.
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| + */
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| + removeAll: function() {
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| + this.listeners_.forEach(EventTracker.removeEventListener_);
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| + this.listeners_ = [];
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| + }
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| + };
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| +
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| + /**
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| + * Remove a single event listener given it's tracker entry. It's up to the
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| + * caller to ensure the entry is removed from listeners_.
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| + * @param {EventTracker.Entry} h The entry describing the listener to remove.
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| + * @private
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| + */
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| + EventTracker.removeEventListener_ = function(h) {
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| + h.node.removeEventListener(h.eventType, h.listener, h.capture);
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| + };
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| +
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| + return EventTracker;
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| +})();
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| +
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