Bug 969506 - TextTrack's ActiveCues should return null of TextTrack's mode is set to 'disabled'. r=rillian

content/media/TextTrack.cpp

@@ -148,7 +148,7 @@ TextTrack::RemoveRegion(const TextTrackRegion& aRegion, ErrorResult& aRv)
 void
 TextTrack::UpdateActiveCueList()
 {
-  if (mMode == TextTrackMode::Disabled || !mTextTrackList) {
+  if (!mTextTrackList) {
     return;
   }
 
@@ -188,15 +188,20 @@ TextTrack::UpdateActiveCueList()
 
 TextTrackCueList*
 TextTrack::GetActiveCues() {
-  UpdateActiveCueList();
-  return mActiveCueList;
+  if (mMode != TextTrackMode::Disabled) {
+    UpdateActiveCueList();
+    return mActiveCueList;
+  }
+  return nullptr;
 }
 
 void
 TextTrack::GetActiveCueArray(nsTArray<nsRefPtr<TextTrackCue> >& aCues)
 {
-  UpdateActiveCueList();
-  mActiveCueList->GetArray(aCues);
+  if (mMode != TextTrackMode::Disabled) {
+    UpdateActiveCueList();
+    mActiveCueList->GetArray(aCues);
+  }
 }
 
 uint16_t

content/media/test/test_texttrackcue.html

@@ -173,6 +173,15 @@ SpecialPowers.pushPrefEnv({"set": [["media.webvtt.enabled", true]]},
 
       is(cueList.length, 6, "Cue list length should be 6.");
 
+      video.currentTime = 2;
+      isnot(trackElement.track.activeCues, null);
+
+      trackElement.track.mode = "disabled";
+      is(trackElement.track.activeCues, null);
+
+      trackElement.track.mode = "showing";
+      video.currentTime = 0;
+
       // Test TextTrack::ActiveCues.
       var cueInfo = [
         { startTime: 0.51, endTime: 0.71, ids: ["Cue 01"] },