PLT-6492 Use new cookie to determine if user is logged in (#6317)

* Use new cookie to determine if user is logged in

* Add temporary code for 3.9 to prevent forced re-login

webapp/actions/global_actions.jsx

@@ -457,7 +457,7 @@ export function clientLogout(redirectTo = '/') {
     ChannelStore.clear();
     stopPeriodicStatusUpdates();
     WebsocketActions.close();
-    localStorage.removeItem('currentUserId');
+    document.cookie = 'MMUSERID=;expires=Thu, 01 Jan 1970 00:00:01 GMT;';
     window.location.href = redirectTo;
 }
 

webapp/actions/user_actions.jsx

@@ -51,8 +51,6 @@ import {getTeamMembersByIds, getMyTeamMembers} from 'mattermost-redux/actions/te
 export function loadMe(callback) {
     loadMeRedux()(dispatch, getState).then(
         () => {
-            localStorage.setItem('currentUserId', UserStore.getCurrentId());
-
             if (callback) {
                 callback();
             }
@@ -741,7 +739,6 @@ export function webLogin(loginId, password, token, success, error) {
     login(loginId, password, token)(dispatch, getState).then(
         (ok) => {
             if (ok && success) {
-                localStorage.setItem('currentUserId', UserStore.getCurrentId());
                 success();
             } else if (!ok && error) {
                 const serverError = getState().requests.users.login.error;