Update notifications API after review.

ui/notifications/notification_types.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 "ui/notifications/notification_types.h"
 
 namespace ui {
 
 namespace notifications {
 
 const char kMessageIntentKey[] = "message_intent";
 const char kPriorityKey[] = "priority";
 const char kTimestampKey[] = "timestamp";
 const char kUnreadCountKey[] = "unread_count";
 const char kButtonOneTitleKey[] = "button_one_title";
 const char kButtonOneIconUrlKey[] = "button_one_icon_url";
 const char kButtonTwoTitleKey[] = "button_two_title";
 const char kButtonTwoIconUrlKey[] = "button_two_icon_url";
 const char kExpandedMessageKey[] = "expanded_message";
 const char kImageUrlKey[] = "image_url";
 const char kItemsKey[] = "items";
 const char kItemTitleKey[] = "title";
 const char kItemMessageKey[] = "message";
 
-const char kSimpleType[] = "simple";
-const char kBaseFormatType[] = "base";
-const char kImageType[] = "image";
-const char kMultipleType[] = "multiple";
-
-NotificationType StringToNotificationType(std::string& string_type) {
-  // In case of unrecognized string, fall back to most common type.
-  return (string_type == kSimpleType) ? NOTIFICATION_TYPE_SIMPLE :
-         (string_type == kBaseFormatType) ? NOTIFICATION_TYPE_BASE_FORMAT :
-         (string_type == kImageType) ? NOTIFICATION_TYPE_IMAGE :
-         (string_type == kMultipleType) ? NOTIFICATION_TYPE_MULTIPLE :
-         NOTIFICATION_TYPE_SIMPLE;
-}
-
 }  // namespace notifications
 
 }  // namespace ui