feat(startMutedPolicy): Uses metadata for startMuted policy. (#2759)

* feat(startMutedPolicy): Uses metadata for startMuted policy.

* squash: Make sure we add boolean.

* squash: Fix lint.

* squash: Ignore policy when set locally.

* squash: Adds a comment.

* squash: Fix lint errors.

JitsiConference.js

     // Do not apply the startMutedPolicy locally on the moderator, the moderator should join with available local
     // sources and the policy needs to be applied only on users that join the call after.
     // this.startMutedPolicy = policy;
+    // TODO: to remove using presence for startmuted policy after old clients update
+    // we keep presence to update UI of old clients
     this.room.addOrReplaceInPresence('startmuted', {
         attributes: {
             audio: policy.audio,
             xmlns: 'http://jitsi.org/jitmeet/start-muted'
         }
     }) && this.room.sendPresence();
+
+    // we want to ignore applying startMutedPolicy locally when we set it
+    this._ignoreFirstStartMutedPolicyUpdate = true;
+
+    this.getMetadataHandler().setMetadata('startMuted', {
+        audio: policy.audio,
+        video: policy.video
+    });
+};
+
+/**
+ * Updates conference startMuted policy if needed and fires an event.
+ *
+ * @param {boolean} audio if audio should be muted.
+ * @param {boolean} video if video should be muted.
+ */
+JitsiConference.prototype._updateStartMutedPolicy = function(audio, video) {
+    if (this._ignoreFirstStartMutedPolicyUpdate) {
+        this._ignoreFirstStartMutedPolicyUpdate = false;
+
+        return;
+    }
+
+    let updated = false;
+
+    if (audio !== this.startMutedPolicy.audio) {
+        this.startMutedPolicy.audio = audio;
+        updated = true;
+    }
+
+    if (video !== this.startMutedPolicy.video) {
+        this.startMutedPolicy.video = video;
+        updated = true;
+    }
+
+    if (updated) {
+        this.eventEmitter.emit(
+            JitsiConferenceEvents.START_MUTED_POLICY_CHANGED,
+            this.startMutedPolicy
+        );
+    }
 };
 
 /**

JitsiConferenceEventManager.js

             }
         });
 
-    chatRoom.addPresenceListener('startmuted', (data, from) => {
-        // Ignore the strartmuted policy if the presence is received from self. The moderator should join with
-        // available local sources and the policy needs to be applied only on users that join the call after.
-        if (conference.myUserId() === from) {
-            return;
-        }
-        const participant = conference.getParticipantById(from);
-
-        if (!participant || !participant.isModerator()) {
-            return;
-        }
-        const startAudioMuted = data.attributes.audio === 'true';
-        const startVideoMuted = data.attributes.video === 'true';
-
-        let updated = false;
-
-        if (startAudioMuted !== conference.startMutedPolicy.audio) {
-            conference.startMutedPolicy.audio = startAudioMuted;
-            updated = true;
-        }
-
-        if (startVideoMuted !== conference.startMutedPolicy.video) {
-            conference.startMutedPolicy.video = startVideoMuted;
-            updated = true;
-        }
-
-        if (updated) {
-            conference.eventEmitter.emit(
-                JitsiConferenceEvents.START_MUTED_POLICY_CHANGED,
-                conference.startMutedPolicy
-            );
-        }
-    });
-
     // Breakout rooms.
     this.chatRoomForwarder.forward(XMPPEvents.BREAKOUT_ROOMS_MOVE_TO_ROOM,
         JitsiConferenceEvents.BREAKOUT_ROOMS_MOVE_TO_ROOM);
         JitsiConferenceEvents.BREAKOUT_ROOMS_UPDATED);
 
     // Room metadata.
-    this.chatRoomForwarder.forward(XMPPEvents.ROOM_METADATA_UPDATED,
-        JitsiConferenceEvents.METADATA_UPDATED);
+    chatRoom.addListener(XMPPEvents.ROOM_METADATA_UPDATED, metadata => {
+        if (metadata.startMuted) {
+            conference._updateStartMutedPolicy(
+                metadata.startMuted.audio || false,
+                metadata.startMuted.video || false
+            );
+        }
+        conference.eventEmitter.emit(JitsiConferenceEvents.METADATA_UPDATED, metadata);
+    });
 };
 
 /**