Fix bug whereby refreshing Vector would not allow querying of membership state

This was caused by Vector only sending a room alias with the `view_room` action.
We now resolve this to a room ID if we don't have a room ID.

src/ScalarMessaging.js

@@ -256,6 +256,7 @@ function returnStateEvent(event, roomId, eventType, stateKey) {
 }
 
 var currentRoomId = null;
+var currentRoomAlias = null;
 
 // Listen for when a room is viewed
 dis.register(onAction);
@@ -264,6 +265,7 @@ function onAction(payload) {
         return;
     }
     currentRoomId = payload.room_id;
+    currentRoomAlias = payload.room_alias;
 }
 
 const onMessage = function(event) {
@@ -287,11 +289,20 @@ const onMessage = function(event) {
         sendError(event, "Missing room_id in request");
         return;
     }
+    let promise = Promise.resolve(currentRoomId);
     if (!currentRoomId) {
+        if (!currentRoomAlias) {
             sendError(event, "Must be viewing a room");
-        return;
         }
-    if (roomId !== currentRoomId) {
+        // no room ID but there is an alias, look it up.
+        console.log("Looking up alias " + currentRoomAlias);
+        promise = MatrixClientPeg.get().getRoomIdForAlias(currentRoomAlias).then((res) => {
+            return res.room_id;
+        });
+    }
+
+    promise.then((viewingRoomId) => {
+        if (roomId !== viewingRoomId) {
             sendError(event, "Room " + roomId + " not visible");
             return;
         }
@@ -326,6 +337,10 @@ const onMessage = function(event) {
                 console.warn("Unhandled postMessage event with action '" + event.data.action +"'");
                 break;
         }
+    }, (err) => {
+        console.error(err);
+        sendError(event, "Failed to lookup current room.");
+    })
 };
 
 module.exports = {