Bug 1550633 - part6 : clear track's cues list whenever track element's src attribute set, changed or removed. r=jya,baku

According to the spec [1], we should empty track's cue list whenever a track element has its src attribute set, changed, or removed.

[1] https://html.spec.whatwg.org/multipage/media.html#sourcing-out-of-band-text-tracks:attr-track-src

Differential Revision: https://phabricator.services.mozilla.com/D31552

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

dom/html/HTMLTrackElement.cpp

@@ -214,17 +214,11 @@ bool HTMLTrackElement::ParseAttribute(int32_t aNamespaceID, nsAtom* aAttribute,
 
 void HTMLTrackElement::SetSrc(const nsAString& aSrc, ErrorResult& aError) {
   SetHTMLAttr(nsGkAtoms::src, aSrc, aError);
-  uint16_t oldReadyState = ReadyState();
   SetReadyState(TextTrackReadyState::NotLoaded);
   if (!mMediaParent) {
     return;
   }
-  if (mTrack && (oldReadyState != TextTrackReadyState::NotLoaded)) {
-    // Remove all the cues in MediaElement.
-    mMediaParent->RemoveTextTrack(mTrack);
-    // Recreate mTrack.
-    CreateTextTrack();
-  }
+
   // Stop WebVTTListener.
   mListener = nullptr;
   if (mChannel) {
@@ -235,6 +229,16 @@ void HTMLTrackElement::SetSrc(const nsAString& aSrc, ErrorResult& aError) {
   MaybeDispatchLoadResource();
 }
 
+void HTMLTrackElement::MaybeClearAllCues() {
+  // Empty track's cue list whenever the track element's `src` attribute set,
+  // changed, or removed,
+  // https://html.spec.whatwg.org/multipage/media.html#sourcing-out-of-band-text-tracks:attr-track-src
+  if (!mTrack) {
+    return;
+  }
+  mTrack->ClearAllCues();
+}
+
 // This function will run partial steps from `start-the-track-processing-model`
 // and finish the rest of steps in `LoadResource()` during the stable state.
 // https://html.spec.whatwg.org/multipage/media.html#start-the-track-processing-model
@@ -463,5 +467,17 @@ void HTMLTrackElement::NotifyShutdown() {
   mListener = nullptr;
 }
 
+nsresult HTMLTrackElement::AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
+                                        const nsAttrValue* aValue,
+                                        const nsAttrValue* aOldValue,
+                                        nsIPrincipal* aMaybeScriptedPrincipal,
+                                        bool aNotify) {
+  if (aNameSpaceID == kNameSpaceID_None && aName == nsGkAtoms::src) {
+    MaybeClearAllCues();
+  }
+  return nsGenericHTMLElement::AfterSetAttr(
+      aNameSpaceID, aName, aValue, aOldValue, aMaybeScriptedPrincipal, aNotify);
+}
+
 }  // namespace dom
 }  // namespace mozilla

dom/html/HTMLTrackElement.h

@@ -87,6 +87,12 @@ class HTMLTrackElement final : public nsGenericHTMLElement {
                               nsIContent* aBindingParent) override;
   virtual void UnbindFromTree(bool aDeep, bool aNullParent) override;
 
+  virtual nsresult AfterSetAttr(int32_t aNameSpaceID, nsAtom* aName,
+                                const nsAttrValue* aValue,
+                                const nsAttrValue* aOldValue,
+                                nsIPrincipal* aMaybeScriptedPrincipal,
+                                bool aNotify) override;
+
   void DispatchTrackRunnable(const nsString& aEventName);
   void DispatchTrustedEvent(const nsAString& aName);
 
@@ -121,6 +127,8 @@ class HTMLTrackElement final : public nsGenericHTMLElement {
   void LoadResource(RefPtr<WebVTTListener>&& aWebVTTListener);
   bool mLoadResourceDispatched;
 
+  void MaybeClearAllCues();
+
   RefPtr<WindowDestroyObserver> mWindowDestroyObserver;
 };
 

dom/media/TextTrack.cpp

@@ -197,6 +197,14 @@ void TextTrack::RemoveCue(TextTrackCue& aCue, ErrorResult& aRv) {
   }
 }
 
+void TextTrack::ClearAllCues() {
+  WEBVTT_LOG("ClearAllCues");
+  ErrorResult dummy;
+  while (!mCueList->IsEmpty()) {
+    RemoveCue(*(*mCueList)[0], dummy);
+  }
+}
+
 void TextTrack::SetCuesDirty() {
   for (uint32_t i = 0; i < mCueList->Length(); i++) {
     ((*mCueList)[i])->Reset();

dom/media/TextTrack.h

@@ -114,6 +114,8 @@ class TextTrack final : public DOMEventTargetHelper {
                                   RefPtr<TextTrackCueList>& aOtherCues,
                                   const media::TimeInterval& aInterval) const;
 
+  void ClearAllCues();
+
  private:
   ~TextTrack();