Add conference duration timer, get conference started timestamp (#1014)

JitsiConferenceEventManager.js

 
             conference.eventEmitter.emit(JitsiConferenceEvents.STARTED_MUTED);
         });
+
+    this._addConferenceXMPPListener(XMPPEvents.CONFERENCE_TIMESTAMP_RECEIVED,
+        createdTimestamp => {
+            conference.eventEmitter.emit(JitsiConferenceEvents.CONFERENCE_CREATED_TIMESTAMP, createdTimestamp);
+        });
 };
 
 /**

JitsiConferenceEvents.js

  */
 export const DOMINANT_SPEAKER_CHANGED = 'conference.dominantSpeaker';
 
+/**
+ * UTC conference timestamp when first participant joined.
+ */
+export const CONFERENCE_CREATED_TIMESTAMP = 'conference.createdTimestamp';
+
 /**
  * Indicates that DTMF support changed.
  */

modules/xmpp/xmpp.js

                     identities.forEach(identity => {
                         if (identity.type === 'speakerstats') {
                             this.speakerStatsComponentAddress = identity.name;
+                        }
 
-                            this.connection.addHandler(
-                                this._onPrivateMessage.bind(this), null,
-                                'message', null, null);
+                        if (identity.type === 'conference_duration') {
+                            this.conferenceDurationComponentAddress = identity.name;
                         }
                     });
+
+                    if (this.speakerStatsComponentAddress
+                        || this.conferenceDurationComponentAddress) {
+                        this.connection.addHandler(
+                            this._onPrivateMessage.bind(this), null,
+                            'message', null, null);
+                    }
                 })
                 .catch(error => {
                     const errmsg = 'Feature discovery error';
 
     /**
      * A private message is received, message that is not addressed to the muc.
-     * We expect private message coming from speaker stats component if it is
+     * We expect private message coming from plugins component if it is
      * enabled and running.
      *
      * @param {string} msg - The message.
     _onPrivateMessage(msg) {
         const from = msg.getAttribute('from');
 
-        if (!this.speakerStatsComponentAddress
-            || from !== this.speakerStatsComponentAddress) {
+        if (!(from === this.speakerStatsComponentAddress
+            || from === this.conferenceDurationComponentAddress)) {
             return;
         }
 
                 XMPPEvents.SPEAKER_STATS_RECEIVED, parsedJson.users);
         }
 
+        if (parsedJson
+            && parsedJson[JITSI_MEET_MUC_TYPE] === 'conference_duration'
+            && parsedJson.created_timestamp) {
+            this.eventEmitter.emit(
+                XMPPEvents.CONFERENCE_TIMESTAMP_RECEIVED, parsedJson.created_timestamp);
+        }
+
         return true;
     }
 }

service/xmpp/XMPPEvents.js

      */
     SPEAKER_STATS_RECEIVED: 'xmpp.speaker_stats_received',
 
+    /**
+     * Event fired when conference creation timestamp is received.
+     */
+    CONFERENCE_TIMESTAMP_RECEIVED: 'xmpp.conference_timestamp_received',
+
     // Designates an event indicating that we should join the conference with
     // audio and/or video muted.
     START_MUTED_FROM_FOCUS: 'xmpp.start_muted_from_focus',