ash: Add a unit test for the system update tray item

ash/test/test_system_tray_delegate.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 "ash/test/test_system_tray_delegate.h"
 
 #include <string>
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/shell.h"
@@ skipping 55 matching lines @@
     return LoginStatus::NOT_LOGGED_IN;
   if (delegate->IsScreenLocked())
     return LoginStatus::LOCKED;
   return login_status_;
 }
 
 bool TestSystemTrayDelegate::IsUserSupervised() const {
   return login_status_ == LoginStatus::SUPERVISED;
 }
 
+void TestSystemTrayDelegate::GetSystemUpdateInfo(UpdateInfo* info) const {
+  DCHECK(info);
+  // In tests, default to not having an update required.
+  info->severity = UpdateInfo::UPDATE_NORMAL;
+  info->update_required = false;
+  info->factory_reset_required = false;
+}
+
 bool TestSystemTrayDelegate::ShouldShowDisplayNotification() {
   return should_show_display_notification_;
 }
 
 bool TestSystemTrayDelegate::GetSessionStartTime(
     base::TimeTicks* session_start_time) {
   // Just returns TimeTicks::Now(), so the remaining time is always the
   // specified limit. This is useful for testing.
   if (session_length_limit_set_)
     *session_start_time = base::TimeTicks::Now();
   return session_length_limit_set_;
 }
 
 bool TestSystemTrayDelegate::GetSessionLengthLimit(
     base::TimeDelta* session_length_limit) {
   if (session_length_limit_set_)
     *session_length_limit = session_length_limit_;
   return session_length_limit_set_;
 }
 
 void TestSystemTrayDelegate::SignOut() {
   base::MessageLoop::current()->QuitWhenIdle();
 }
 
 }  // namespace test
 }  // namespace ash