put the room name in the title tag

should fix https://github.com/vector-im/riot-web/issues/4454

src/components/structures/MatrixChat.js

@@ -271,6 +271,10 @@ export default createReactClass({
 
         this.focusComposer = false;
 
+        // object field used for tracking the status info appended to the title tag.
+        // we don't do it as react state as i'm scared about triggering needless react refreshes.
+        this.subTitleStatus = '';
+
         // this can technically be done anywhere but doing this here keeps all
         // the routing url path logic together.
         if (this.onAliasClick) {
@@ -1297,6 +1301,7 @@ export default createReactClass({
             collapsedRhs: false,
             currentRoomId: null,
         });
+        this.subTitleStatus = '';
         this._setPageSubtitle();
     },
 
@@ -1312,6 +1317,7 @@ export default createReactClass({
             collapsedRhs: false,
             currentRoomId: null,
         });
+        this.subTitleStatus = '';
         this._setPageSubtitle();
     },
 
@@ -1706,6 +1712,7 @@ export default createReactClass({
         if (this.props.onNewScreen) {
             this.props.onNewScreen(screen);
         }
+        this._setPageSubtitle();
     },
 
     onAliasClick: function(event, alias) {
@@ -1821,7 +1828,13 @@ export default createReactClass({
     },
 
     _setPageSubtitle: function(subtitle='') {
-        document.title = `${SdkConfig.get().brand || 'Riot'} ${subtitle}`;
+        if (this.state.currentRoomId) {
+            const room = MatrixClientPeg.get().getRoom(this.state.currentRoomId);
+            if (room) {
+                subtitle = `| ${ room.name }`;
+            }
+        }
+        document.title = `${SdkConfig.get().brand || 'Riot'} ${subtitle} ${this.subTitleStatus}`;
     },
 
     updateStatusIndicator: function(state, prevState) {
@@ -1832,15 +1845,15 @@ export default createReactClass({
             PlatformPeg.get().setNotificationCount(notifCount);
         }
 
-        let subtitle = '';
+        this.subTitleStatus = '';
         if (state === "ERROR") {
-            subtitle += `[${_t("Offline")}] `;
+            this.subTitleStatus += `[${_t("Offline")}] `;
         }
         if (notifCount > 0) {
-            subtitle += `[${notifCount}]`;
+            this.subTitleStatus += `[${notifCount}]`;
         }
 
-        this._setPageSubtitle(subtitle);
+        this._setPageSubtitle();
     },
 
     onCloseAllSettings() {