This CL replaces std::string user_id in ash/* with AccountId.

ash/system/user/user_view.cc

 // Copyright 2014 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 "ash/system/user/user_view.h"
 
 #include <algorithm>
 
 #include "ash/multi_profile_uma.h"
 #include "ash/popup_message.h"
@@ skipping 60 matching lines @@
   if (ash::Shell::GetInstance()
           ->session_state_delegate()
           ->IsUserSessionBlocked())
     return;
 
   DCHECK(user_index > 0);
   ash::SessionStateDelegate* delegate =
       ash::Shell::GetInstance()->session_state_delegate();
   ash::MultiProfileUMA::RecordSwitchActiveUser(
       ash::MultiProfileUMA::SWITCH_ACTIVE_USER_BY_TRAY);
-  delegate->SwitchActiveUser(
-      delegate->GetUserInfo(user_index)->GetAccountId().GetUserEmail());
+  delegate->SwitchActiveUser(delegate->GetUserInfo(user_index)->GetAccountId());
 }
 
 class LogoutButton : public TrayPopupLabelButton {
  public:
   // If |placeholder| is true, button is used as placeholder. That means that
   // button is inactive and is not painted, but consume the same ammount of
   // space, as if it was painted.
   LogoutButton(views::ButtonListener* listener,
                const base::string16& text,
                bool placeholder)
@@ skipping 458 matching lines @@
   focus_manager_ = NULL;
   if (user_card_view_->GetFocusManager())
     user_card_view_->GetFocusManager()->ClearFocus();
   popup_message_.reset();
   mouse_watcher_.reset();
   add_menu_option_.reset();
 }
 
 }  // namespace tray
 }  // namespace ash