Bug 1531863 - part2 : handle text track mode changed in MediaElement. r=jya

In order to make the implementation more fitting with the spec, move the implementation of `pending-text-track-change-notification-flag` from text track list to media element.

In addition, it also help us not to expose the internal flag `show-poster` (which will be implemented in patch3) of media element when doing the related algorithm.

Differential Revision: https://phabricator.services.mozilla.com/D21810

--HG--
extra : moz-landing-system : lando

dom/html/HTMLMediaElement.cpp

@@ -7375,6 +7375,22 @@ already_AddRefed<Promise> HTMLMediaElement::SetSinkId(const nsAString& aSinkId,
   return promise.forget();
 }
 
+void HTMLMediaElement::NotifyTextTrackModeChanged() {
+  if (mPendingTextTrackChanged) {
+    return;
+  }
+  mPendingTextTrackChanged = true;
+  mAbstractMainThread->Dispatch(
+      NS_NewRunnableFunction("HTMLMediaElement::NotifyTextTrackModeChanged",
+                             [this, self = RefPtr<HTMLMediaElement>(this)]() {
+                               mPendingTextTrackChanged = false;
+                               if (!mTextTrackManager) {
+                                 return;
+                               }
+                               GetTextTracks()->CreateAndDispatchChangeEvent();
+                             }));
+}
+
 }  // namespace dom
 }  // namespace mozilla
 

dom/html/HTMLMediaElement.h

@@ -1674,6 +1674,16 @@ class HTMLMediaElement : public nsGenericHTMLElement,
   // bfcache.
   bool mHasEverBeenBlockedForAutoplay = false;
 
+  // True if we have dispatched a task for text track changed, will be unset
+  // when we starts processing text track changed.
+  // https://html.spec.whatwg.org/multipage/media.html#pending-text-track-change-notification-flag
+  bool mPendingTextTrackChanged = false;
+
+ public:
+  // This function will be called whenever a text track that is in a media
+  // element's list of text tracks has its text track mode change value
+  void NotifyTextTrackModeChanged();
+
  public:
   // Helper class to measure times for playback telemetry stats
   class TimeDurationAccumulator {

dom/media/TextTrack.cpp

@@ -73,33 +73,28 @@ JSObject* TextTrack::WrapObject(JSContext* aCx,
 }
 
 void TextTrack::SetMode(TextTrackMode aValue) {
-  if (mMode != aValue) {
-    mMode = aValue;
-    if (aValue == TextTrackMode::Disabled) {
-      // Remove all the cues in MediaElement.
-      HTMLMediaElement* mediaElement = GetMediaElement();
-      if (mediaElement) {
-        for (size_t i = 0; i < mCueList->Length(); ++i) {
-          mediaElement->NotifyCueRemoved(*(*mCueList)[i]);
-        }
-      }
-      SetCuesInactive();
-    } else {
-      // Add all the cues into MediaElement.
-      HTMLMediaElement* mediaElement = GetMediaElement();
-      if (mediaElement) {
-        for (size_t i = 0; i < mCueList->Length(); ++i) {
-          mediaElement->NotifyCueAdded(*(*mCueList)[i]);
-        }
-      }
-    }
-    if (mTextTrackList) {
-      mTextTrackList->CreateAndDispatchChangeEvent();
-    }
-    // Ensure the TimeMarchesOn is called in case that the mCueList
-    // is empty.
-    NotifyCueUpdated(nullptr);
+  if (mMode == aValue) {
+    return;
   }
+  mMode = aValue;
+
+  HTMLMediaElement* mediaElement = GetMediaElement();
+  if (aValue == TextTrackMode::Disabled) {
+    for (size_t i = 0; i < mCueList->Length() && mediaElement; ++i) {
+      mediaElement->NotifyCueRemoved(*(*mCueList)[i]);
+    }
+    SetCuesInactive();
+  } else {
+    for (size_t i = 0; i < mCueList->Length() && mediaElement; ++i) {
+      mediaElement->NotifyCueAdded(*(*mCueList)[i]);
+    }
+  }
+  if (mediaElement) {
+    mediaElement->NotifyTextTrackModeChanged();
+  }
+  // Ensure the TimeMarchesOn is called in case that the mCueList
+  // is empty.
+  NotifyCueUpdated(nullptr);
 }
 
 void TextTrack::GetId(nsAString& aId) const {

dom/media/TextTrackList.cpp

@@ -118,39 +118,25 @@ class TrackEventRunner : public Runnable {
   RefPtr<Event> mEvent;
 };
 
-class ChangeEventRunner final : public TrackEventRunner {
- public:
-  ChangeEventRunner(TextTrackList* aList, Event* aEvent)
-      : TrackEventRunner(aList, aEvent) {}
-
-  NS_IMETHOD Run() override {
-    mList->mPendingTextTrackChange = false;
-    return TrackEventRunner::Run();
-  }
-};
-
 nsresult TextTrackList::DispatchTrackEvent(Event* aEvent) {
   return DispatchTrustedEvent(aEvent);
 }
 
 void TextTrackList::CreateAndDispatchChangeEvent() {
   MOZ_ASSERT(NS_IsMainThread());
-  if (!mPendingTextTrackChange) {
-    nsPIDOMWindowInner* win = GetOwner();
-    if (!win) {
-      return;
-    }
-
-    mPendingTextTrackChange = true;
-    RefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
-
-    event->InitEvent(NS_LITERAL_STRING("change"), false, false);
-    event->SetTrusted(true);
-
-    nsCOMPtr<nsIRunnable> eventRunner = new ChangeEventRunner(this, event);
-    nsGlobalWindowInner::Cast(win)->Dispatch(TaskCategory::Other,
-                                             eventRunner.forget());
+  nsPIDOMWindowInner* win = GetOwner();
+  if (!win) {
+    return;
   }
+
+  RefPtr<Event> event = NS_NewDOMEvent(this, nullptr, nullptr);
+
+  event->InitEvent(NS_LITERAL_STRING("change"), false, false);
+  event->SetTrusted(true);
+
+  nsCOMPtr<nsIRunnable> eventRunner = new TrackEventRunner(this, event);
+  nsGlobalWindowInner::Cast(win)->Dispatch(TaskCategory::Other,
+                                           eventRunner.forget());
 }
 
 void TextTrackList::CreateAndDispatchTrackEventRunner(

dom/media/TextTrackList.h

@@ -65,8 +65,6 @@ class TextTrackList final : public DOMEventTargetHelper {
   IMPL_EVENT_HANDLER(addtrack)
   IMPL_EVENT_HANDLER(removetrack)
 
-  bool mPendingTextTrackChange = false;
-
  private:
   ~TextTrackList();