tor-browser

commit 92724719a6819d61174ee3d6dd0879c29c7d20cb
parent a091522bd31547e1cbf68cb5f60866119edf4a77
Author: Andreas Pehrson <apehrson@mozilla.com>
Date:   Thu, 23 Oct 2025 14:11:16 +0000

Bug 1771789 - Add and use an API for MediaStreamTrackSource cloning. r=jib

Note, no sources implement it yet.

Differential Revision: https://phabricator.services.mozilla.com/D266381

Diffstat:
M
dom/media/MediaStreamTrack.cpp
 | 
2
++
M
dom/media/MediaStreamTrack.h
 | 
23
+++++++++++++++++++++--

2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/dom/media/MediaStreamTrack.cpp b/dom/media/MediaStreamTrack.cpp
@@ -46,6 +46,8 @@ NS_IMPL_CYCLE_COLLECTION_TRAVERSE_BEGIN(MediaStreamTrackSource)
   NS_IMPL_CYCLE_COLLECTION_TRAVERSE(mPrincipal)
 NS_IMPL_CYCLE_COLLECTION_TRAVERSE_END
 
+auto MediaStreamTrackSource::Clone() -> CloneResult { return {}; }
+
 auto MediaStreamTrackSource::ApplyConstraints(
     const dom::MediaTrackConstraints& aConstraints, CallerType aCallerType)
     -> RefPtr<ApplyConstraintsPromise> {
diff --git a/dom/media/MediaStreamTrack.h b/dom/media/MediaStreamTrack.h
@@ -128,6 +128,18 @@ class MediaStreamTrackSource : public nsISupports {
    */
   virtual void Destroy() {}
 
+  struct CloneResult {
+    RefPtr<MediaStreamTrackSource> mSource;
+    RefPtr<mozilla::MediaTrack> mInputTrack;
+  };
+
+  /**
+   * Clone this MediaStreamTrackSource. Cloned sources allow independent track
+   * settings. Not supported by all source types. A source not supporting
+   * cloning returns nullptr.
+   */
+  virtual CloneResult Clone();
+
   /**
    * Gets the source's MediaSourceEnum for usage by PeerConnections.
    */
@@ -645,8 +657,15 @@ class MediaStreamTrack : public DOMEventTargetHelper, public SupportsWeakPtr {
 
   template <typename TrackType>
   already_AddRefed<MediaStreamTrack> CloneInternal() {
-    auto newTrack = MakeRefPtr<TrackType>(mWindow, mInputTrack, mSource,
-                                          ReadyState(), Muted(), mConstraints);
+    auto cloneRes = mSource->Clone();
+    MOZ_ASSERT(!!cloneRes.mSource == !!cloneRes.mInputTrack);
+    if (!cloneRes.mSource || !cloneRes.mInputTrack) {
+      cloneRes.mSource = mSource;
+      cloneRes.mInputTrack = mInputTrack;
+    }
+    auto newTrack =
+        MakeRefPtr<TrackType>(mWindow, cloneRes.mInputTrack, cloneRes.mSource,
+                              ReadyState(), Muted(), mConstraints);
     newTrack->SetEnabled(Enabled());
     newTrack->SetMuted(Muted());
     return newTrack.forget();