Prevents session_length_timeout reappearing when it's already dismissed.

ash/system/session_length_limit/tray_session_length_limit.cc

 // Copyright (c) 2012 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/session_length_limit/tray_session_length_limit.h"
 
 #include <algorithm>
 
 #include "ash/shelf/shelf_types.h"
 #include "ash/shell.h"
@@ skipping 60 matching lines @@
 
 base::string16 FormatRemainingSessionTimeNotification(
     const base::TimeDelta& remaining_session_time) {
   return l10n_util::GetStringFUTF16(
       IDS_ASH_STATUS_TRAY_REMAINING_SESSION_TIME_NOTIFICATION,
       ui::TimeFormat::TimeDurationLong(remaining_session_time));
 }
 
 void CreateOrUpdateNotification(const base::TimeDelta& remaining_time,
                                 bool enable_spoken_feedback) {
+  message_center::MessageCenter* message_center =
+      message_center::MessageCenter::Get();
+  // If |enable_spoken_feedback| is false, it's just an update of the content,
+  // which should not create a new one if it's already closed.

[stevenjb, 2013/09/09 17:58:03]

nit: s/one/notification

[Jun Mukai, 2013/09/09 19:37:25]

Done.

+  if (!enable_spoken_feedback &&
+      !message_center->HasNotification(kSessionLengthTimeoutNotificationId)) {

[stevenjb, 2013/09/09 17:58:03]

This seems awkward; we're effectively using 'enable_spoken_feedback' as
'create'. I think it would be more clear if this logic were moved to Update().

[Jun Mukai, 2013/09/09 19:37:25]

I don't think I need to separate the function / logic here, instead rename the
|enable_spoken_feedback| flag to another name, |state_changed|.

[stevenjb, 2013/09/09 19:43:07]

OK, that's more clear now.

+    return;
+  }
+
   ui::ResourceBundle& bundle = ui::ResourceBundle::GetSharedInstance();
   message_center::RichNotificationData data;
   data.should_make_spoken_feedback_for_popup_updates = enable_spoken_feedback;
   scoped_ptr<Notification> notification(new Notification(
       message_center::NOTIFICATION_TYPE_SIMPLE,
       kSessionLengthTimeoutNotificationId,
       FormatRemainingSessionTimeNotification(remaining_time),
       base::string16() /* message */,
       bundle.GetImageNamed(IDR_AURA_UBER_TRAY_SESSION_LENGTH_LIMIT_TIMER),
       base::string16() /* display_source */,
@@ skipping 263 matching lines @@
   }
 
   // Update the tray view last so that it can check whether the notification
   // view is currently visible or not.
   if (tray_view_)
     tray_view_->Update();
 }
 
 }  // namespace internal
 }  // namespace ash