We should use UserID object to identify users instead of username.

chrome/browser/ui/ash/launcher/multi_profile_browser_status_monitor.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/ash/launcher/multi_profile_browser_status_monitor.h"
 
 #include "ash/shelf/shelf_util.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/profiles/profile_manager.h"
 #include "chrome/browser/ui/ash/launcher/chrome_launcher_controller.h"
@@ skipping 11 matching lines @@
 MultiProfileBrowserStatusMonitor::MultiProfileBrowserStatusMonitor(
     ChromeLauncherController* launcher_controller)
     : BrowserStatusMonitor(launcher_controller),
       launcher_controller_(launcher_controller) {
 }
 
 MultiProfileBrowserStatusMonitor::~MultiProfileBrowserStatusMonitor() {
 }
 
 void MultiProfileBrowserStatusMonitor::ActiveUserChanged(
-    const std::string& user_email) {
+    const user_manager::UserID& user_id) {
   // Handle windowed apps.
   for (AppList::iterator it = app_list_.begin(); it != app_list_.end(); ++it) {
     bool owned = multi_user_util::IsProfileFromActiveUser((*it)->profile());
     bool shown = IsV1AppInShelf(*it);
     if (owned && !shown)
       ConnectV1AppToLauncher(*it);
     else if (!owned && shown)
       DisconnectV1AppFromLauncher(*it);
   }
 
@@ skipping 90 matching lines @@
 
 void MultiProfileBrowserStatusMonitor::DisconnectV1AppFromLauncher(
     Browser* browser) {
   // Removing a V1 app from the launcher requires to remove the content and
   // the launcher item.
   launcher_controller_->UpdateAppState(
       browser->tab_strip_model()->GetActiveWebContents(),
       ChromeLauncherController::APP_STATE_REMOVED);
   BrowserStatusMonitor::RemoveV1AppFromShelf(browser);
 }