show Guest instead of random username when in guest mode

src/components/structures/TopLeftMenuButton.js

@@ -22,6 +22,7 @@ import AccessibleButton from '../views/elements/AccessibleButton';
 import BaseAvatar from '../views/avatars/BaseAvatar';
 import MatrixClientPeg from '../../MatrixClientPeg';
 import Avatar from '../../Avatar';
+import { _t } from '../../languageHandler';
 
 const AVATAR_SIZE = 28;
 
@@ -70,7 +71,14 @@ export default class TopLeftMenuButton extends React.Component {
     render() {
         const fallbackUserId = MatrixClientPeg.get().getUserId();
         const profileInfo = this.state.profileInfo;
-        const name = profileInfo ? profileInfo.name : fallbackUserId;
+        let name;
+        if (MatrixClientPeg.get().isGuest()) {
+            name = _t("Guest");
+        } else if (profileInfo) {
+            name = profileInfo.name;
+        } else {
+            name = fallbackUserId;
+        }
         let nameElement;
         if (!this.props.collapsed) {
             nameElement = <div className="mx_TopLeftMenuButton_name">

src/i18n/strings/en_EN.json

@@ -1497,5 +1497,6 @@
     "If you didn't remove the recovery method, an attacker may be trying to access your account. Change your account password and set a new recovery method immediately in Settings.": "If you didn't remove the recovery method, an attacker may be trying to access your account. Change your account password and set a new recovery method immediately in Settings.",
     "Failed to set direct chat tag": "Failed to set direct chat tag",
     "Failed to remove tag %(tagName)s from room": "Failed to remove tag %(tagName)s from room",
-    "Failed to add tag %(tagName)s to room": "Failed to add tag %(tagName)s to room"
+    "Failed to add tag %(tagName)s to room": "Failed to add tag %(tagName)s to room",
+    "Guest": "Guest"
 }