Fixes tray_session_length_limit_unittest timeout on valgrind.

ash/system/chromeos/session/tray_session_length_limit_unittest.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/chromeos/session/tray_session_length_limit.h"
 
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "ash/system/tray/system_tray.h"
 #include "ash/test/ash_test_base.h"
@@ skipping 12 matching lines @@
   ~TraySessionLengthLimitTest() override {}
 
   void SetUp() override {
     AshTestBase::SetUp();
     SystemTray* system_tray =
         Shell::GetPrimaryRootWindowController()->GetSystemTray();
     tray_session_length_limit_ = new TraySessionLengthLimit(system_tray);
     system_tray->AddTrayItem(tray_session_length_limit_);
   }
 
-  void TearDown() override { AshTestBase::TearDown(); }
+  void TearDown() override {
+    ClearSessionLengthLimit();
+    AshTestBase::TearDown();
+  }
 
  protected:
   void UpdateSessionLengthLimitInMin(int mins) {
     GetSystemTrayDelegate()->SetSessionLengthLimitForTest(
         base::TimeDelta::FromMinutes(mins));
     tray_session_length_limit_->OnSessionLengthLimitChanged();
   }
 
   message_center::Notification* GetNotification() {
     const message_center::NotificationList::Notifications& notifications =
         message_center::MessageCenter::Get()->GetVisibleNotifications();
     for (message_center::NotificationList::Notifications::const_iterator iter =
              notifications.begin(); iter != notifications.end(); ++iter) {
       if ((*iter)->id() == TraySessionLengthLimit::kNotificationId)
         return *iter;
     }
-    return NULL;
+    return nullptr;
   }
 
   void ClearSessionLengthLimit() {
     GetSystemTrayDelegate()->ClearSessionLengthLimit();
     tray_session_length_limit_->OnSessionLengthLimitChanged();
   }
 
   void RemoveNotification() {
     message_center::MessageCenter::Get()->RemoveNotification(
         TraySessionLengthLimit::kNotificationId, false /* by_user */);
@@ skipping 52 matching lines @@
   // Should read again because an increase of the remaining time is noteworthy.
   EXPECT_TRUE(notification->rich_notification_data().
               should_make_spoken_feedback_for_popup_updates);
 
   // Clears the limit: the notification should be gone.
   ClearSessionLengthLimit();
   EXPECT_FALSE(GetNotification());
 }
 
 TEST_F(TraySessionLengthLimitTest, RemoveNotification) {
-  message_center::Notification* notification;
-
   // Limit is 15 min.
   UpdateSessionLengthLimitInMin(15);
   EXPECT_TRUE(GetNotification());
 
   // Removes the notification.
   RemoveNotification();
   EXPECT_FALSE(GetNotification());
 
   // Limit is 10 min. The notification should not re-appear.
   UpdateSessionLengthLimitInMin(10);
   EXPECT_FALSE(GetNotification());
 
   // Limit is 3 min. The notification should re-appear and should be re-read
   // because of state change.
   UpdateSessionLengthLimitInMin(3);
-  notification = GetNotification();
+  message_center::Notification* notification = GetNotification();
   EXPECT_TRUE(notification);
   EXPECT_TRUE(notification->rich_notification_data().
               should_make_spoken_feedback_for_popup_updates);
 
   RemoveNotification();
 
   // Session length limit is updated to longer state. Notification should
   // re-appear and be re-read.
   UpdateSessionLengthLimitInMin(15);
   notification = GetNotification();
   EXPECT_TRUE(notification);
   EXPECT_TRUE(notification->rich_notification_data().
               should_make_spoken_feedback_for_popup_updates);
 }
 
 }  // namespace test
 }  // namespace ash