Don’t process update end until buffered value has been set

In Firefox, the updateend event is triggered for both removing from the buffer and adding to the buffer. To prevent our update end handler from executing on removals, we wait for segmentInfo to have a filled in buffered value before we continue processing.

@@ -1229,13 +1229,20 @@ videojs.HlsHandler.prototype.updateEndHandler_ = function () {
     seekable,
     timelineUpdate;
 
-  this.pendingSegment_ = null;
-
   // stop here if the update errored or was aborted
   if (!segmentInfo) {
     return;
   }
 
+  // In Firefox, the updateend event is triggered for both removing from the buffer and
+  // adding to the buffer. To prevent this code from executing on removals, we wait for
+  // segmentInfo to have a filled in buffered value before we continue processing.
+  if (!segmentInfo.buffered) {
+    return;
+  }
+
+  this.pendingSegment_ = null;
+
   playlist = this.playlists.media();
   segments = playlist.segments;
   currentMediaIndex = segmentInfo.mediaIndex + (segmentInfo.mediaSequence - playlist.mediaSequence);

@@ -2906,6 +2906,40 @@ test('does not download segments if preload option set to none', function() {
   equal(requests.length, 0, 'did not download any segments');
 });
 
+test('does not process update end until buffered value has been set', function() {
+  var drainBufferCallCount = 0, origDrainBuffer;
+
+  player.src({
+    src: 'master.m3u8',
+    type: 'application/vnd.apple.mpegurl'
+  });
+  origDrainBuffer = player.tech_.hls.drainBuffer;
+  player.tech_.hls.drainBuffer = function() {
+    drainBufferCallCount++;
+  };
+
+  openMediaSource(player);
+  standardXHRResponse(requests.shift()); // master
+  standardXHRResponse(requests.shift()); // media
+
+  equal(drainBufferCallCount, 0, 'drainBuffer not called yet');
+
+  standardXHRResponse(requests.shift()); // segment
+
+  ok(player.tech_.hls.pendingSegment_, 'pending segment exists');
+  equal(drainBufferCallCount, 1, 'drainBuffer called');
+
+  player.tech_.hls.sourceBuffer.trigger('updateend');
+  ok(player.tech_.hls.pendingSegment_, 'pending segment exists');
+
+  player.tech_.hls.drainBuffer = origDrainBuffer;
+  player.tech_.hls.drainBuffer();
+  ok(player.tech_.hls.pendingSegment_, 'pending segment exists');
+
+  player.tech_.hls.sourceBuffer.trigger('updateend');
+  ok(!player.tech_.hls.pendingSegment_, 'pending segment cleared out');
+});
+
 module('Buffer Inspection');
 
 test('detects time range end-point changed by updates', function() {