Have Player Use Destroyer

Changed the player to use shaka.util.Destroyer so that player
can be protected against multiple calls to destroy.

Change-Id: Ib255e465966e700eb8b8418281657ecb8b852eba

lib/player.js

@@ -60,9 +60,6 @@ goog.require('shaka.util.StreamUtils');
 shaka.Player = function(video, dependencyInjector) {
   shaka.util.FakeEventTarget.call(this);
 
-  /** @private {boolean} */
-  this.destroyed_ = false;
-
   /** @private {HTMLMediaElement} */
   this.video_ = null;
 
@@ -184,7 +181,25 @@ shaka.Player = function(video, dependencyInjector) {
   if (video) {
     this.attach(video, true /* initializeMediaSource */);
   }
+
+  /** @private {!shaka.util.Destroyer} */
+  this.destroyer_ = new shaka.util.Destroyer(async () => {
+    // Then, destroy other components and clear fields.
+    let p = Promise.all([
+      this.eventManager_ ? this.eventManager_.destroy() : null,
+      this.networkingEngine_ ? this.networkingEngine_.destroy() : null,
+    ]);
+
+    this.textVisibility_ = false;
+    this.eventManager_ = null;
+    this.abrManager_ = null;
+    this.networkingEngine_ = null;
+    this.config_ = null;
+
+    await p;
+  });
 };
+
 goog.inherits(shaka.Player, shaka.util.FakeEventTarget);
 
 
@@ -219,23 +234,12 @@ shaka.Player.prototype.cancelLoad_ = function() {
  */
 shaka.Player.prototype.destroy = async function() {
   // First, detach from the media element.  This implies unloading content
-  // and canceling pending loads.
+  // and canceling pending loads.  This must be called before the destroyer
+  // as it will indirectly check if the player has already been destroyed and
+  // won't execute as expected.  Calling detach multiple times is safe, so it
+  // is okay to be outside the protection of the destroyer.
   await this.detach();
-  // Then, destroy other components and clear fields.
-
-  this.destroyed_ = true;
-
-  let p = Promise.all([
-    this.eventManager_ ? this.eventManager_.destroy() : null,
-    this.networkingEngine_ ? this.networkingEngine_.destroy() : null,
-  ]);
-
-  this.textVisibility_ = false;
-  this.eventManager_ = null;
-  this.abrManager_ = null;
-  this.networkingEngine_ = null;
-  this.config_ = null;
-  await p;
+  await this.destroyer_.destroy();
 };
 
 
@@ -1344,7 +1348,7 @@ shaka.Player.prototype.isBuffering = function() {
  * @export
  */
 shaka.Player.prototype.unload = async function(reinitializeMediaSource) {
-  if (this.destroyed_) {
+  if (this.destroyer_.destroyed()) {
     return;
   }
 
@@ -2021,7 +2025,9 @@ shaka.Player.prototype.addTextTrack = function(
   // Don't create the media state until subtitles are actually enabled
   return this.streamingEngine_.loadNewTextStream(
       stream, this.textVisibility_).then(function() {
-    if (this.destroyed_) return;
+    if (this.destroyer_.destroyed()) {
+      return;
+    }
 
     let curPeriodIdx = this.manifest_.periods.indexOf(period);
     let activeText = this.streamingEngine_.getActiveText();
@@ -2727,7 +2733,9 @@ shaka.Player.prototype.onChangePeriod_ = function() {
  * @private
  */
 shaka.Player.prototype.updateState_ = function() {
-  if (this.destroyed_) return;
+  if (this.destroyer_.destroyed()) {
+    return;
+  }
 
   let newState;
   if (this.buffering_) {
@@ -3033,7 +3041,10 @@ shaka.Player.prototype.onAdaptation_ = function() {
   // This gives StreamingEngine time to absorb the changes before the user
   // tries to query them.
   Promise.resolve().then(function() {
-    if (this.destroyed_) return;
+    if (this.destroyer_.destroyed()) {
+      return;
+    }
+
     let event = new shaka.util.FakeEvent('adaptation');
     this.dispatchEvent(event);
   }.bind(this));
@@ -3049,7 +3060,10 @@ shaka.Player.prototype.onTracksChanged_ = function() {
   // This gives StreamingEngine time to absorb the changes before the user
   // tries to query them.
   Promise.resolve().then(function() {
-    if (this.destroyed_) return;
+    if (this.destroyer_.destroyed()) {
+      return;
+    }
+
     let event = new shaka.util.FakeEvent('trackschanged');
     this.dispatchEvent(event);
   }.bind(this));
@@ -3069,7 +3083,9 @@ shaka.Player.prototype.onTextTrackVisibility_ = function() {
  */
 shaka.Player.prototype.onError_ = function(error) {
   // Errors dispatched after destroy is called are irrelevant.
-  if (this.destroyed_) return;
+  if (this.destroyer_.destroyed()) {
+    return;
+  }
 
   goog.asserts.assert(error instanceof shaka.util.Error, 'Wrong error type!');