Support for room upgrades

For https://github.com/vector-im/riot-web/issues/7164

src/base-apis.js

@@ -446,6 +446,18 @@ function(roomId, includeMembership, excludeMembership, atEventId, callback) {
     return this._http.authedRequest(callback, "GET", path);
 };
 
+/**
+ * Upgrades a room to a new protocol version
+ * @param {string} roomId
+ * @param {string} newVersion The target version to upgrade to
+ * @return {module:client.Promise} Resolves: Object with key 'replacement_room'
+ * @return {module:http-api.MatrixError} Rejects: with an error response.
+ */
+MatrixBaseApis.prototype.upgradeRoom = function(roomId, newVersion) {
+    const path = utils.encodeUri("/rooms/$roomId/upgrade", {$roomId: roomId});
+    return this._http.authedRequest(undefined, "POST", path, undefined, {new_version: newVersion});
+};
+
 
 /**
  * @param {string} groupId

src/models/room.js

@@ -29,6 +29,9 @@ const EventTimelineSet = require("./event-timeline-set");
 
 import ReEmitter from '../ReEmitter';
 
+//const LATEST_ROOM_VERSION = '1';
+const LATEST_ROOM_VERSION = 'badger';
+
 function synthesizeReceipt(userId, event, receiptType) {
     // console.log("synthesizing receipt for "+event.getId());
     // This is really ugly because JS has no way to express an object literal
@@ -200,6 +203,27 @@ Room.prototype.getVersion = function() {
     return ver;
 };
 
+/**
+ * Determines whether this room needs to be upgraded to a new version
+ * @returns {string?} What version the room should be upgraded to, or null if
+ *     the room does not require upgrading at this time.
+ */
+Room.prototype.shouldUpgradeToVersion = function() {
+    // This almost certainly won't be the way this actually works - this
+    // is essentially a stub method.
+    if (this.getVersion() === LATEST_ROOM_VERSION) return null;
+    return LATEST_ROOM_VERSION;
+};
+
+/**
+ * Determines whether the given user is permitted to perform a room upgrade
+ * @param {String} userId The ID of the user to test against
+ * @returns {bool} True if the given user is permitted to upgrade the room
+ */
+Room.prototype.userMayUpgradeRoom = function(userId) {
+    return this.currentState.maySendStateEvent("m.room.tombstone", userId);
+};
+
 /**
  * Get the list of pending sent events for this room
  *