Added plumbing to get and transmit multiple-item notification data

ui/notifications/notification_types.h

 // 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.
 
 #ifndef UI_NOTIFICATIONS_NOTIFICATION_TYPES_H_
 #define UI_NOTIFICATIONS_NOTIFICATION_TYPES_H_
 
 #include <string>
 
 #include "ui/base/ui_export.h"
 
 namespace ui {
 
 namespace notifications {
 
 // Keys for optional fields in Notification.
 UI_EXPORT extern const char kMessageIntentKey[];
 UI_EXPORT extern const char kPriorityKey[];
 UI_EXPORT extern const char kTimestampKey[];
 UI_EXPORT extern const char kSecondIconUrlKey[];
 UI_EXPORT extern const char kUnreadCountKey[];
 UI_EXPORT extern const char kButtonOneTitleKey[];
 UI_EXPORT extern const char kButtonOneIntentKey[];
 UI_EXPORT extern const char kButtonTwoTitleKey[];
 UI_EXPORT extern const char kButtonTwoIntentKey[];
 UI_EXPORT extern const char kExpandedMessageKey[];
 UI_EXPORT extern const char kImageUrlKey[];
+UI_EXPORT extern const char kItemsKey[];
+UI_EXPORT extern const char kItemTitleKey[];
+UI_EXPORT extern const char kItemMessageKey[];
 
 enum NotificationType {
   NOTIFICATION_TYPE_SIMPLE,
   NOTIFICATION_TYPE_BASE_FORMAT,
   NOTIFICATION_TYPE_MULTIPLE,
 };
 
 UI_EXPORT NotificationType StringToNotificationType(std::string& string_type);
 
 }  // namespace notifications
 
 }  // namespace ui
 
 #endif // UI_NOTIFICATIONS_NOTIFICATION_TYPES_H_