Bug 1592287 - Remove ended captureStream tracks and fire "removetrack" on MediaStream. r=jib

Differential Revision: https://phabricator.services.mozilla.com/D52816

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

dom/html/HTMLMediaElement.cpp

@@ -897,6 +897,8 @@ void ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
                                  HTMLMediaElement::OutputMediaStream& aField,
                                  const char* aName, uint32_t aFlags) {
   ImplCycleCollectionTraverse(aCallback, aField.mStream, "mStream", aFlags);
+  ImplCycleCollectionTraverse(aCallback, aField.mLiveTracks, "mLiveTracks",
+                              aFlags);
   ImplCycleCollectionTraverse(aCallback, aField.mFinishWhenEndedLoadingSrc,
                               "mFinishWhenEndedLoadingSrc", aFlags);
   ImplCycleCollectionTraverse(aCallback, aField.mFinishWhenEndedAttrStream,
@@ -905,6 +907,7 @@ void ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
 
 void ImplCycleCollectionUnlink(HTMLMediaElement::OutputMediaStream& aField) {
   ImplCycleCollectionUnlink(aField.mStream);
+  ImplCycleCollectionUnlink(aField.mLiveTracks);
   ImplCycleCollectionUnlink(aField.mFinishWhenEndedLoadingSrc);
   ImplCycleCollectionUnlink(aField.mFinishWhenEndedAttrStream);
 }
@@ -3326,6 +3329,8 @@ void HTMLMediaElement::AddOutputTrackSourceToOutputStream(
                                     aSource->Track(), aSource);
   }
 
+  aOutputStream.mLiveTracks.AppendElement(domTrack);
+
   switch (aMode) {
     case AddTrackMode::ASYNC:
       mMainThreadEventTarget->Dispatch(
@@ -3413,6 +3418,27 @@ void HTMLMediaElement::UpdateOutputTrackSources() {
         NewRunnableMethod("MediaElementTrackSource::OverrideEnded", source,
                           &MediaElementTrackSource::OverrideEnded));
 
+    // Remove the track from the MediaStream after it ended.
+    for (OutputMediaStream& ms : mOutputStreams) {
+      if (source->Track()->mType == MediaSegment::VIDEO &&
+          ms.mCapturingAudioOnly) {
+        continue;
+      }
+      DebugOnly<size_t> length = ms.mLiveTracks.Length();
+      ms.mLiveTracks.RemoveElementsBy(
+          [&](const RefPtr<MediaStreamTrack>& aTrack) {
+            if (&aTrack->GetSource() != source) {
+              return false;
+            }
+            mMainThreadEventTarget->Dispatch(
+                NewRunnableMethod<RefPtr<MediaStreamTrack>>(
+                    "DOMMediaStream::RemoveTrackInternal", ms.mStream,
+                    &DOMMediaStream::RemoveTrackInternal, aTrack));
+            return true;
+          });
+      MOZ_ASSERT(ms.mLiveTracks.Length() == length - 1);
+    }
+
     mOutputTrackSources.Remove(id);
   }
 

dom/html/HTMLMediaElement.h

@@ -123,6 +123,7 @@ class HTMLMediaElement : public nsGenericHTMLElement,
     ~OutputMediaStream();
 
     RefPtr<DOMMediaStream> mStream;
+    nsTArray<RefPtr<MediaStreamTrack>> mLiveTracks;
     const bool mCapturingAudioOnly;
     const bool mFinishWhenEnded;
     // If mFinishWhenEnded is true, this is the URI of the first resource

dom/media/DOMMediaStream.cpp

@@ -397,6 +397,16 @@ void DOMMediaStream::AddTrackInternal(MediaStreamTrack* aTrack) {
   DispatchTrackEvent(NS_LITERAL_STRING("addtrack"), aTrack);
 }
 
+void DOMMediaStream::RemoveTrackInternal(MediaStreamTrack* aTrack) {
+  LOG(LogLevel::Debug,
+      ("DOMMediaStream %p Removing owned track %p", this, aTrack));
+  if (!HasTrack(*aTrack)) {
+    return;
+  }
+  RemoveTrack(*aTrack);
+  DispatchTrackEvent(NS_LITERAL_STRING("removetrack"), aTrack);
+}
+
 already_AddRefed<nsIPrincipal> DOMMediaStream::GetPrincipal() {
   nsCOMPtr<nsIPrincipal> principal =
       nsGlobalWindowInner::Cast(mWindow)->GetPrincipal();

dom/media/DOMMediaStream.h

@@ -171,6 +171,16 @@ class DOMMediaStream : public DOMEventTargetHelper,
    */
   void AddTrackInternal(MediaStreamTrack* aTrack);
 
+  /**
+   * Removes a MediaStreamTrack from mTracks and fires "removetrack" if it
+   * was removed.
+   *
+   * Note that "removetrack" is raised synchronously and only has an effect if
+   * this MediaStream is already exposed to script. For spec compliance this is
+   * to be called from an async task.
+   */
+  void RemoveTrackInternal(MediaStreamTrack* aTrack);
+
   /**
    * Add an nsISupports object that this stream will keep alive as long as
    * the stream itself is alive.