2 files changed, 28 insertions, 5 deletions
diff --git a/components/script/dom/mediastream.rs b/components/script/dom/mediastream.rs
index a5edb458337..2ae573b290e 100644
--- a/components/script/dom/mediastream.rs
+++ b/components/script/dom/mediastream.rs
@@ -4,12 +4,14 @@
 
 use crate::dom::bindings::cell::DomRefCell;
 use crate::dom::bindings::codegen::Bindings::MediaStreamBinding::{self, MediaStreamMethods};
+use crate::dom::bindings::error::Fallible;
 use crate::dom::bindings::reflector::{reflect_dom_object, DomObject};
 use crate::dom::bindings::root::{Dom, DomRoot};
 use crate::dom::bindings::str::DOMString;
 use crate::dom::eventtarget::EventTarget;
 use crate::dom::globalscope::GlobalScope;
 use crate::dom::mediastreamtrack::MediaStreamTrack;
+use crate::dom::window::Window;
 use dom_struct::dom_struct;
 use servo_media::streams::MediaStreamType;
 use std::cell::Ref;
@@ -36,6 +38,27 @@ impl MediaStream {
         )
     }
 
+    pub fn Constructor(global: &Window) -> Fallible<DomRoot<MediaStream>> {
+        Ok(MediaStream::new(&global.global()))
+    }
+
+    pub fn Constructor_(_: &Window, stream: &MediaStream) -> Fallible<DomRoot<MediaStream>> {
+        Ok(stream.Clone())
+    }
+
+    pub fn Constructor__(
+        global: &Window,
+        tracks: Vec<DomRoot<MediaStreamTrack>>,
+    ) -> Fallible<DomRoot<MediaStream>> {
+        let new = MediaStream::new(&global.global());
+        for track in tracks {
+            // this is quadratic, but shouldn't matter much
+            // if this becomes a problem we can use a hash map
+            new.AddTrack(&track)
+        }
+        Ok(new)
+    }
+
     pub fn get_tracks(&self) -> Ref<[Dom<MediaStreamTrack>]> {
         Ref::map(self.tracks.borrow(), |tracks| &**tracks)
     }
diff --git a/components/script/dom/webidls/MediaStream.webidl b/components/script/dom/webidls/MediaStream.webidl
index 7483cde2d36..b1d5664a7f7 100644
--- a/components/script/dom/webidls/MediaStream.webidl
+++ b/components/script/dom/webidls/MediaStream.webidl
@@ -4,11 +4,11 @@
 
 // https://w3c.github.io/mediacapture-main/#dom-mediastream
 
-// [Exposed=Window,
-//  Constructor,
-//  Constructor(MediaStream stream),
-//  Constructor(sequence<MediaStreamTrack> tracks)]
-[Exposed=Window, Pref="dom.webrtc.enabled"]
+[Exposed=Window,
+ Constructor,
+ Constructor(MediaStream stream),
+ Constructor(sequence<MediaStreamTrack> tracks),
+Pref="dom.webrtc.enabled"]
 interface MediaStream : EventTarget {
     // readonly        attribute DOMString id;
     sequence<MediaStreamTrack> getAudioTracks();