ash: Use enum for SessionController::CycleActiveUser

ash/common/session/session_controller.cc

 // Copyright 2016 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/common/session/session_controller.h"
 
 #include <algorithm>
 
 #include "ash/common/session/session_state_observer.h"
 #include "base/bind.h"
@@ skipping 55 matching lines @@
 void SessionController::LockScreen() {
   if (client_)
     client_->RequestLockScreen();
 }
 
 void SessionController::SwitchActiveUser(const AccountId& account_id) {
   if (client_)
     client_->SwitchActiveUser(account_id);
 }
 
-void SessionController::CycleActiveUser(bool next_user) {
+void SessionController::CycleActiveUser(CycleUserDirection direction) {
   if (client_)
-    client_->CycleActiveUser(next_user);
+    client_->CycleActiveUser(direction);
 }
 
 void SessionController::AddSessionStateObserver(
     SessionStateObserver* observer) {
   observers_.AddObserver(observer);
 }
 
 void SessionController::RemoveSessionStateObserver(
     SessionStateObserver* observer) {
   observers_.RemoveObserver(observer);
@@ skipping 68 matching lines @@
 void SessionController::AddUserSession(mojom::UserSessionPtr user_session) {
   const AccountId account_id(user_session->account_id);
 
   user_sessions_.push_back(std::move(user_session));
 
   for (auto& observer : observers_)
     observer.UserAddedToSession(account_id);
 }
 
 }  // namespace ash