MPRIS Plugin: don't export players unless they're in the playerList

Occasionally kdeconnect-android will send player updates for recently
destroyed players. Instead of creating players when we receive their
state, create and destroy stub players based on the list we receive and
ignore updates for players not in the list.

fixes #830

src/service/plugins/mpris.js

@@ -102,15 +102,24 @@ var Plugin = GObject.registerClass({
      * @param {array} playerList - A list of remote player names
      */
     _handlePlayerList(playerList) {
+        // First destroy removed players
         for (let player of this._players.values()) {
             if (!playerList.includes(player.Identity)) {
                 this._players.delete(player.Identity);
                 player.destroy();
             }
         }
 
+        // Then add new players before requesting their state
         for (let identity of playerList) {
-            this._device.sendPacket({
+            if (!this._players.has(identity)) {
+                this._players.set(
+                    identity,
+                    new RemotePlayer(this.device, identity)
+                );
+            }
+
+            this.device.sendPacket({
                 type: 'kdeconnect.mpris.request',
                 body: {
                     player: identity,
@@ -129,10 +138,7 @@ var Plugin = GObject.registerClass({
     _handlePlayerState(state) {
         let player = this._players.get(state.player);
 
-        if (player === undefined) {
-            player = new RemotePlayer(this.device, state);
-            this._players.set(state.player, player);
-        } else {
+        if (player !== undefined) {
             player.parseState(state);
         }
     }
@@ -513,18 +519,17 @@ var RemotePlayer = GObject.registerClass({
     }
 }, class RemotePlayer extends GObject.Object {
 
-    _init(device, initialState) {
+    _init(device, identity) {
         super._init();
 
         this._device = device;
+        this._Identity = identity;
         this._isPlaying = false;
 
         this._ownerId = 0;
         this._connection = null;
         this._applicationIface = null;
         this._playerIface = null;
-
-        this.parseState(initialState);
     }
 
     async export() {