Make Lifecycle.loadSession return an explicit result

- rather than inferring it from the fact it didn't call logging_in.

src/Lifecycle.js

@@ -62,6 +62,8 @@ import { _t } from './languageHandler';
  *     true; defines the IS to use.
  *
  * @returns {Promise} a promise which resolves when the above process completes.
+ *     Resolves to `true` if we ended up starting a session, or `false` if we
+ *     failed.
  */
 export function loadSession(opts) {
     const fragmentQueryParams = opts.fragmentQueryParams || {};
@@ -86,12 +88,12 @@ export function loadSession(opts) {
             homeserverUrl: guestHsUrl,
             identityServerUrl: guestIsUrl,
             guest: true,
-        }, true);
+        }, true).then(() => true);
     }
 
     return _restoreFromLocalStorage().then((success) => {
         if (success) {
-            return;
+            return true;
         }
 
         if (enableGuest) {
@@ -99,6 +101,7 @@ export function loadSession(opts) {
         }
 
         // fall back to login screen
+        return false;
     });
 }
 
@@ -176,9 +179,10 @@ function _registerAsGuest(hsUrl, isUrl, defaultDeviceDisplayName) {
             homeserverUrl: hsUrl,
             identityServerUrl: isUrl,
             guest: true,
-        }, true);
+        }, true).then(() => true);
     }, (err) => {
         console.error("Failed to register as guest: " + err + " " + err.data);
+        return false;
     });
 }
 

src/components/structures/MatrixChat.js

@@ -335,10 +335,12 @@ module.exports = React.createClass({
                 });
             }).catch((e) => {
                 console.error("Unable to load session", e);
-            }).then(()=>{
-                // stuff this through the dispatcher so that it happens
-                // after the on_logged_in action.
-                dis.dispatch({action: 'load_completed'});
+                return false;
+            }).then((loadedSession) => {
+                if (!loadedSession) {
+                    // fall back to showing the login screen
+                    dis.dispatch({action: "start_login"});
+                }
             });
         }).done();
     },
@@ -560,9 +562,6 @@ module.exports = React.createClass({
             case 'will_start_client':
                 this._onWillStartClient();
                 break;
-            case 'load_completed':
-                this._onLoadCompleted();
-                break;
             case 'new_version':
                 this.onVersion(
                     payload.currentVersion, payload.newVersion,
@@ -892,17 +891,6 @@ module.exports = React.createClass({
         });
     },
 
-    /**
-     * Called when the sessionloader has finished
-     */
-    _onLoadCompleted: function() {
-        // if we've got this far without leaving the 'loading' view, then
-        // login must have failed, so start the login process
-        if (this.state.view === VIEWS.LOADING) {
-            dis.dispatch({action: "start_login"});
-        }
-    },
-
     /**
      * Called whenever someone changes the theme
      *