From 24d795335e0f741b1fa262382469d88bd74f201a Mon Sep 17 00:00:00 2001
From: Garrett Singer <gesinger@gmail.com>
Date: Mon, 23 Nov 2015 23:39:58 -0800
Subject: [PATCH] Prevent non native text tracks from leaking cuechange event
 listeners

---
 src/js/tech/tech.js             |  7 +++--
 test/unit/tracks/tracks.test.js | 46 +++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/src/js/tech/tech.js b/src/js/tech/tech.js
index 866bf81a93..d1c8bc92a7 100644
--- a/src/js/tech/tech.js
+++ b/src/js/tech/tech.js
@@ -321,9 +321,8 @@ class Tech extends Component {
       window['WebVTT'] = true;
     }
 
-    let textTracksChanges = Fn.bind(this, function() {
-      let updateDisplay = () => this.trigger('texttrackchange');
-
+    let updateDisplay = () => this.trigger('texttrackchange');
+    let textTracksChanges = () => {
       updateDisplay();
 
       for (let i = 0; i < tracks.length; i++) {
@@ -333,7 +332,7 @@ class Tech extends Component {
           track.addEventListener('cuechange', updateDisplay);
         }
       }
-    });
+    };
 
     tracks.addEventListener('change', textTracksChanges);
 
diff --git a/test/unit/tracks/tracks.test.js b/test/unit/tracks/tracks.test.js
index 7a51f465b9..05e71ed127 100644
--- a/test/unit/tracks/tracks.test.js
+++ b/test/unit/tracks/tracks.test.js
@@ -2,6 +2,7 @@ import ChaptersButton from '../../../src/js/control-bar/text-track-controls/chap
 import SubtitlesButton from '../../../src/js/control-bar/text-track-controls/subtitles-button.js';
 import CaptionsButton from '../../../src/js/control-bar/text-track-controls/captions-button.js';
 
+import TextTrack from '../../../src/js/tracks/text-track.js';
 import TextTrackDisplay from '../../../src/js/tracks/text-track-display.js';
 import Html5 from '../../../src/js/tech/html5.js';
 import Flash from '../../../src/js/tech/flash.js';
@@ -342,3 +343,48 @@ if (Html5.supportsNativeTextTracks()) {
     emulatedTt.on('addtrack', addtrack);
   });
 }
+
+test('removes cuechange event when text track is hidden for emulated tracks', function() {
+  let player = TestHelpers.makePlayer();
+  let tt = new TextTrack({
+    tech: player.tech_,
+    mode: 'showing'
+  });
+  tt.addCue({
+    id: '1',
+    startTime: 2,
+    endTime: 5
+  });
+  player.tech_.textTracks().addTrack_(tt);
+  player.tech_.emulateTextTracks();
+
+  let numTextTrackChanges = 0;
+  player.tech_.on('texttrackchange', function() {
+    numTextTrackChanges++;
+  });
+
+  tt.mode = 'showing';
+  equal(numTextTrackChanges, 1,
+    'texttrackchange should be called once for mode change');
+  tt.mode = 'showing';
+  equal(numTextTrackChanges, 2,
+    'texttrackchange should be called once for mode change');
+
+  player.tech_.currentTime = function() {
+    return 3;
+  };
+  player.tech_.trigger('timeupdate');
+  equal(numTextTrackChanges, 3,
+    'texttrackchange should be triggered once for the cuechange');
+
+  tt.mode = 'hidden';
+  equal(numTextTrackChanges, 4,
+    'texttrackchange should be called once for the mode change');
+
+  player.tech_.currentTime = function() {
+    return 7;
+  };
+  player.tech_.trigger('timeupdate');
+  equal(numTextTrackChanges, 4,
+    'texttrackchange should be not be called since mode is hidden');
+});