Auto merge of #23342 - Manishearth:webrtc-streams, r=ferjm

Receive streams in WebRTC (and MediaStreamTrack support)

This adds the `ontrack` event handler to webrtc, and all the `MediaStreamTrack` stuff necessary to make it work.

WebRTC has the ability to group media tracks into streams using MSIDs, but I haven't yet figured out how to do this. For now, `ontrack` should work.

This _should_ be complete, but it hasn't yet been tested (hence the WIP)

r? @ferjm or @jdm

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components/script/dom/webidls/MediaStream.webidl

@@ -4,20 +4,20 @@
 
 // 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();
-    // sequence<MediaStreamTrack> getVideoTracks();
-    // sequence<MediaStreamTrack> getTracks();
-    // MediaStreamTrack? getTrackById(DOMString trackId);
-    // void addTrack(MediaStreamTrack track);
-    // void removeTrack(MediaStreamTrack track);
-    // MediaStream clone();
+    sequence<MediaStreamTrack> getAudioTracks();
+    sequence<MediaStreamTrack> getVideoTracks();
+    sequence<MediaStreamTrack> getTracks();
+    MediaStreamTrack? getTrackById(DOMString trackId);
+    void addTrack(MediaStreamTrack track);
+    void removeTrack(MediaStreamTrack track);
+    MediaStream clone();
     // readonly        attribute boolean active;
     //                 attribute EventHandler onaddtrack;
     //                 attribute EventHandler onremovetrack;

components/script/dom/webidls/MediaStreamTrack.webidl

@@ -0,0 +1,24 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://w3c.github.io/mediacapture-main/#dom-mediastreamtrack
+
+[Exposed=Window, Pref="dom.webrtc.enabled"]
+interface MediaStreamTrack : EventTarget {
+    readonly        attribute DOMString kind;
+    readonly        attribute DOMString id;
+    // readonly        attribute DOMString label;
+    //                 attribute boolean enabled;
+    // readonly        attribute boolean muted;
+    //                 attribute EventHandler onmute;
+    //                 attribute EventHandler onunmute;
+    // readonly        attribute MediaStreamTrackState readyState;
+    //                 attribute EventHandler onended;
+    MediaStreamTrack clone();
+    // void stop();
+    // MediaTrackCapabilities getCapabilities();
+    // MediaTrackConstraints getConstraints();
+    // MediaTrackSettings getSettings();
+    // Promise<void> applyConstraints(optional MediaTrackConstraints constraints);
+};

components/script/dom/webidls/RTCPeerConnection.webidl

@@ -114,3 +114,15 @@ enum RTCSignalingState {
     "have-remote-pranswer",
     "closed"
 };
+
+partial interface RTCPeerConnection {
+    // sequence<RTCRtpSender>      getSenders();
+    // sequence<RTCRtpReceiver>    getReceivers();
+    // sequence<RTCRtpTransceiver> getTransceivers();
+    // RTCRtpSender                addTrack(MediaStreamTrack track,
+    //                                      MediaStream... streams);
+    // void                        removeTrack(RTCRtpSender sender);
+    // RTCRtpTransceiver           addTransceiver((MediaStreamTrack or DOMString) trackOrKind,
+    //                                            optional RTCRtpTransceiverInit init);
+    attribute EventHandler ontrack;
+};

components/script/dom/webidls/RTCTrackEvent.webidl

@@ -0,0 +1,23 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+// https://w3c.github.io/webrtc-pc/#dom-rtctrackevent
+
+[Constructor(DOMString type, RTCTrackEventInit eventInitDict),
+ Exposed=Window, Pref="dom.webrtc.enabled"]
+interface RTCTrackEvent : Event {
+    // readonly attribute RTCRtpReceiver           receiver;
+    readonly attribute MediaStreamTrack         track;
+    // [SameObject]
+    // readonly attribute FrozenArray<MediaStream> streams;
+    // readonly attribute RTCRtpTransceiver        transceiver;
+};
+
+// https://www.w3.org/TR/webrtc/#dom-rtctrackeventinit
+dictionary RTCTrackEventInit : EventInit {
+    // required RTCRtpReceiver        receiver;
+    required MediaStreamTrack      track;
+             // sequence<MediaStream> streams = [];
+    // required RTCRtpTransceiver     transceiver;
+};