Remove unused `GROUPS_CHANGED` event listener in groups service

This event is never broadcast anywhere. A comment referenced this being
called when a user leaves a group, but this is handled in the `streamer`
service by calling `groups.load()` directly.

src/sidebar/events.js

@@ -11,8 +11,6 @@ module.exports = {
 
   // Session state changes
 
-  /** The list of groups changed */
-  GROUPS_CHANGED: 'groupsChanged',
   /** The logged-in user changed */
   USER_CHANGED: 'userChanged',
   /**

src/sidebar/services/groups.js

@@ -130,12 +130,6 @@ function groups($rootScope, store, api, isSidebar, localStorage, serviceUrl, ses
     }
   });
 
-  // reset the focused group if the user leaves it
-  $rootScope.$on(events.GROUPS_CHANGED, function () {
-    // return for use in test
-    return load();
-  });
-
   // refetch the list of groups when user changes
   $rootScope.$on(events.USER_CHANGED, () => {
     // FIXME Makes a second api call on page load. better way?

src/sidebar/services/test/groups-test.js

@@ -68,7 +68,7 @@ describe('groups', function() {
       },
 
       $on: function(event, callback) {
-        if (event === events.GROUPS_CHANGED || event === events.USER_CHANGED || event === events.FRAME_CONNECTED) {
+        if (event === events.USER_CHANGED || event === events.FRAME_CONNECTED) {
           this.eventCallbacks[event] = callback;
         }
       },
@@ -250,18 +250,13 @@ describe('groups', function() {
   });
 
   describe('calls load on various events', function () {
-    var changeEvents = [
-      {event: events.GROUPS_CHANGED},
-      {event: events.USER_CHANGED},
-    ];
-
-    unroll('should fetch the list of groups from the server when #event occurs', function (testCase) {
+    it('refetches groups when the logged-in user changes', () => {
       service();
 
-      return fakeRootScope.eventCallbacks[testCase.event]().then(() => {
+      return fakeRootScope.eventCallbacks[events.USER_CHANGED]().then(() => {
         assert.calledOnce(fakeApi.groups.list);
       });
-    }, changeEvents);
+    });
 
     context('when a new frame connects', () => {
       it('should refetch groups if main frame URL has changed', () => {