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 58 matching lines @@
   return base::IntToString16(value);
 }
 
 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));
 }
 
+// Creates, or updates the notification for session length timeout with
+// |remaining_time|.  |state_changed| is true when it's internal state has been

[bartfab (slow), 2013/09/09 20:36:30]

Nit: s/it's/its/

[Jun Mukai, 2013/09/09 20:44:25]

Done.

+// changed from another.
 void CreateOrUpdateNotification(const base::TimeDelta& remaining_time,
-                                bool enable_spoken_feedback) {
+                                bool state_changed) {
+  message_center::MessageCenter* message_center =
+      message_center::MessageCenter::Get();
+
+  // Do not create a new notification if no state has changed. It may happen
+  // when the notification is already closed by the user, see crbug.com/285941.
+  if (!state_changed &&
+      !message_center->HasNotification(kSessionLengthTimeoutNotificationId)) {
+    return;
+  }
+
   ui::ResourceBundle& bundle = ui::ResourceBundle::GetSharedInstance();
   message_center::RichNotificationData data;
-  data.should_make_spoken_feedback_for_popup_updates = enable_spoken_feedback;
+  // Makes the spoken feedback only when the state has been changed.
+  data.should_make_spoken_feedback_for_popup_updates = state_changed;
   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 */,
       message_center::NotifierId(NOTIFIER_SESSION_LENGTH_TIMEOUT),
       data,
       NULL /* delegate */));
@@ skipping 260 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