Simplify FakeEvent and FakeEventTarget

We now avoid tricky things like CustomEvent and setting properties on
native Events.  This gives us better cross-browser compatibility and
less complexity.

Change-Id: Idc9fcc69c33257e4540d956bcbc949de6d992cf0

build/types/polyfill

@@ -1,6 +1,5 @@
 # Polyfills used to emulate missing browsers features.
 
-+../../lib/polyfill/customevent.js
 +../../lib/polyfill/fullscreen.js
 +../../lib/polyfill/mediakeys.js
 +../../lib/polyfill/patchedmediakeys_20140218.js

lib/polyfill/patchedmediakeys_20140218.js

@@ -369,7 +369,7 @@ shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeys.prototype.
 shaka.polyfill.PatchedMediaKeys.v20140218.
     MediaKeySession = function(nativeMediaKeys, sessionType) {
   shaka.log.debug('v20140218.MediaKeySession');
-  shaka.util.FakeEventTarget.call(this, null);
+  shaka.util.FakeEventTarget.call(this);
 
   // Native MediaKeySession, which will be created in generateRequest
   /** @private {MSMediaKeySession} */
@@ -520,8 +520,7 @@ shaka.polyfill.PatchedMediaKeys.v20140218.onMsNeedKey_ = function(event) {
   // Alias
   var v20140218 = shaka.polyfill.PatchedMediaKeys.v20140218;
 
-  var event2 = shaka.util.FakeEvent.create({
-    type: 'encrypted',
+  var event2 = new shaka.util.FakeEvent('encrypted', {
     initDataType: 'cenc',
     initData: v20140218.NormaliseInitData_(event.initData)
   });
@@ -615,8 +614,7 @@ shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeySession.prototype.
 
   var isNew = this.keyStatuses.getStatus() == undefined;
 
-  var event2 = shaka.util.FakeEvent.create({
-    type: 'message',
+  var event2 = new shaka.util.FakeEvent('message', {
     messageType: isNew ? 'licenserequest' : 'licenserenewal',
     message: event.message.buffer
   });
@@ -711,7 +709,7 @@ shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeySession.prototype.
 shaka.polyfill.PatchedMediaKeys.v20140218.MediaKeySession.prototype.
     updateKeyStatus_ = function(status) {
   this.keyStatuses.setStatus(status);
-  var event = shaka.util.FakeEvent.create({type: 'keystatuseschange'});
+  var event = new shaka.util.FakeEvent('keystatuseschange');
   this.dispatchEvent(event);
 };
 

lib/polyfill/patchedmediakeys_v01b.js

@@ -404,8 +404,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeys.prototype.onWebkitNeedKey_ =
   shaka.log.debug('v01b.onWebkitNeedKey_', event);
   shaka.asserts.assert(this.media_, 'media_ not set in onWebkitNeedKey_');
 
-  var event2 = shaka.util.FakeEvent.create({
-    type: 'encrypted',
+  var event2 = new shaka.util.FakeEvent('encrypted', {
     initDataType: 'webm',  // not used by v0.1b EME, but given a valid value
     initData: event.initData
   });
@@ -430,8 +429,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeys.prototype.onWebkitKeyMessage_ =
 
   var isNew = session.keyStatuses.getStatus() == undefined;
 
-  var event2 = shaka.util.FakeEvent.create({
-    type: 'message',
+  var event2 = new shaka.util.FakeEvent('message', {
     messageType: isNew ? 'licenserequest' : 'licenserenewal',
     message: event.message
   });
@@ -514,7 +512,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeys.prototype.findSession_ =
 shaka.polyfill.PatchedMediaKeys.v01b.MediaKeySession =
     function(media, keySystem, sessionType) {
   shaka.log.debug('v01b.MediaKeySession');
-  shaka.util.FakeEventTarget.call(this, null);
+  shaka.util.FakeEventTarget.call(this);
 
   /** @private {!HTMLMediaElement} */
   this.media_ = media;
@@ -788,7 +786,7 @@ shaka.polyfill.PatchedMediaKeys.v01b.MediaKeySession.prototype.update_ =
 shaka.polyfill.PatchedMediaKeys.v01b.MediaKeySession.prototype.
     updateKeyStatus_ = function(status) {
   this.keyStatuses.setStatus(status);
-  var event = shaka.util.FakeEvent.create({type: 'keystatuseschange'});
+  var event = new shaka.util.FakeEvent('keystatuseschange');
   this.dispatchEvent(event);
 };
 

lib/util/fake_event.js

@@ -17,35 +17,85 @@
 
 goog.provide('shaka.util.FakeEvent');
 
-goog.require('shaka.asserts');
 
 
 /**
- * @namespace shaka.util.FakeEvent
- * @summary A utility to simplify the creation of fake events.
+ * Create an Event work-alike object based on the dictionary.
+ * The event should contain all of the same properties from the dict.
+ *
+ * @param {string} type
+ * @param {Object=} opt_dict
+ * @constructor
+ * @extends {Event}
+ */
+shaka.util.FakeEvent = function(type, opt_dict) {
+  // Take properties from dict if present.
+  var dict = opt_dict || {};
+  for (var key in dict) {
+    this[key] = dict[key];
+  }
+
+
+  // These Properties below cannot be set by dict.  They are all provided for
+  // compatibility with native events.
+
+  /** @const {boolean} */
+  this.bubbles = false;
+
+  /** @const {boolean} */
+  this.cancelable = false;
+
+  /** @const {boolean} */
+  this.defaultPrevented = false;
+
+  /**
+   * According to MDN, Chrome uses high-res timers instead of epoch time.
+   * Follow suit so that timeStamps on FakeEvents use the same base as
+   * on native Events.
+   * @const {number}
+   * @see https://developer.mozilla.org/en-US/docs/Web/API/Event/timeStamp
+   */
+  this.timeStamp = window.performance ? window.performance.now() : Date.now();
+
+  /** @const {string} */
+  this.type = type;
+
+  /** @const {boolean} */
+  this.isTrusted = false;
+
+  /** @type {EventTarget} */
+  this.currentTarget = null;
+
+  /** @type {EventTarget} */
+  this.target = null;
+
+
+  /**
+   * Non-standard property read by FakeEventTarget to stop processing listeners.
+   * @type {boolean}
+   */
+  this.stopped = false;
+};
+
+
+/**
+ * Does nothing, since FakeEvents have no default.  Provided for compatibility
+ * with native Events.
  */
+shaka.util.FakeEvent.prototype.preventDefault = function() {};
 
 
 /**
- * Return an Event object based on the dictionary.
- * The event should contain all of the same properties from the dict.
- * @param {!Object} dict
- * @return {!Event}
+ * Stops processing event listeners for this event.  Provided for compatibility
+ * with native Events.
  */
-shaka.util.FakeEvent.create = function(dict) {
-  var event = new CustomEvent(dict.type, {
-    detail: dict.detail,
-    bubbles: !!dict.bubbles
-  });
-  // NOTE: In strict mode, we can't overwrite existing properties, so we only
-  // set properties on "event" which don't exist yet.  If a property does exist
-  // on "event", we assert that it has the correct value already.
-  for (var key in dict) {
-    if (key in event) {
-      shaka.asserts.assert(event[key] == dict[key], 'key = ' + key);
-    } else {
-      event[key] = dict[key];
-    }
-  }
-  return event;
+shaka.util.FakeEvent.prototype.stopImmediatePropagation = function() {
+  this.stopped = true;
 };
+
+
+/**
+ * Does nothing, since FakeEvents do not bubble.  Provided for compatibility
+ * with native Events.
+ */
+shaka.util.FakeEvent.prototype.stopPropagation = function() {};