2 files changed, 20 insertions, 19 deletions
diff --git a/components/script/dom/mediasession.rs b/components/script/dom/mediasession.rs
index 6d9afa592e0..70e63f3fd58 100644
--- a/components/script/dom/mediasession.rs
+++ b/components/script/dom/mediasession.rs
@@ -14,7 +14,7 @@ use crate::dom::mediametadata::MediaMetadata;
 use crate::dom::window::Window;
 use crate::script_thread::ScriptThread;
 use dom_struct::dom_struct;
-use msg::constellation_msg::PipelineId;
+use msg::constellation_msg::TopLevelBrowsingContextId;
 use std::rc::Rc;
 
 #[dom_struct]
@@ -28,22 +28,20 @@ pub struct MediaSession {
 
 impl MediaSession {
     #[allow(unrooted_must_root)]
-    fn new_inherited(pipeline_id: PipelineId) -> MediaSession {
+    fn new_inherited(browsing_context_id: TopLevelBrowsingContextId) -> MediaSession {
         let media_session = MediaSession {
             reflector_: Reflector::new(),
             metadata: Default::default(),
             playback_state: DomRefCell::new(MediaSessionPlaybackState::None),
         };
-        ScriptThread::register_media_session(&media_session, pipeline_id);
+        ScriptThread::register_media_session(&media_session, browsing_context_id);
         media_session
     }
 
     pub fn new(window: &Window) -> DomRoot<MediaSession> {
-        let pipeline_id = window
-            .pipeline_id()
-            .expect("Cannot create MediaSession without a PipelineId");
+        let browsing_context_id = window.window_proxy().top_level_browsing_context_id();
         reflect_dom_object(
-            Box::new(MediaSession::new_inherited(pipeline_id)),
+            Box::new(MediaSession::new_inherited(browsing_context_id)),
             window,
             MediaSessionBinding::Wrap,
         )
@@ -83,10 +81,10 @@ impl MediaSessionMethods for MediaSession {
 impl Drop for MediaSession {
     fn drop(&mut self) {
         let global = self.global();
-        let pipeline_id = global
+        let browsing_context_id = global
             .as_window()
-            .pipeline_id()
-            .expect("No PipelineId while dropping MediaSession");
-        ScriptThread::remove_media_session(pipeline_id);
+            .window_proxy()
+            .top_level_browsing_context_id();
+        ScriptThread::remove_media_session(browsing_context_id);
     }
 }
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 5aec6a8a57d..2bd7cc4907b 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -698,10 +698,10 @@ pub struct ScriptThread {
     /// Code is running as a consequence of a user interaction
     is_user_interacting: Cell<bool>,
 
-    /// The MediaSessions registered for this Pipeline, if any.
-    /// There can only be one active MediaSession. The constellation
-    /// has the PipelineId of the active MediaSession, if any.
-    media_sessions: DomRefCell<HashMap<PipelineId, Dom<MediaSession>>>,
+    /// The MediaSessions known by this thread, if any.
+    /// There can only be one active MediaSession.
+    /// The constellation has the BrowsingContextId of the active MediaSession, if any.
+    media_sessions: DomRefCell<HashMap<TopLevelBrowsingContextId, Dom<MediaSession>>>,
 }
 
 /// In the event of thread panic, all data on the stack runs its destructor. However, there
@@ -3956,23 +3956,26 @@ impl ScriptThread {
         )
     }
 
-    pub fn register_media_session(media_session: &MediaSession, pipeline_id: PipelineId) {
+    pub fn register_media_session(
+        media_session: &MediaSession,
+        browsing_context_id: TopLevelBrowsingContextId,
+    ) {
         SCRIPT_THREAD_ROOT.with(|root| {
             let script_thread = unsafe { &*root.get().unwrap() };
             script_thread
                 .media_sessions
                 .borrow_mut()
-                .insert(pipeline_id, Dom::from_ref(media_session));
+                .insert(browsing_context_id, Dom::from_ref(media_session));
         })
     }
 
-    pub fn remove_media_session(pipeline_id: PipelineId) {
+    pub fn remove_media_session(browsing_context_id: TopLevelBrowsingContextId) {
         SCRIPT_THREAD_ROOT.with(|root| {
             let script_thread = unsafe { &*root.get().unwrap() };
             script_thread
                 .media_sessions
                 .borrow_mut()
-                .remove(&pipeline_id);
+                .remove(&browsing_context_id);
         })
     }
 }