Make //content responsible for generating notification Ids

chrome/browser/notifications/message_center_display_service.cc

 // Copyright 2016 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 "chrome/browser/notifications/message_center_display_service.h"
 
 #include "chrome/browser/notifications/notification.h"
 #include "chrome/browser/notifications/notification_ui_manager.h"
 #include "chrome/browser/profiles/profile.h"
 
@@ skipping 23 matching lines @@
 
 bool MessageCenterDisplayService::GetDisplayed(
     std::set<std::string>* notifications) const {
   DCHECK(notifications);
   for (auto notification_id : ui_manager_->GetAllIdsByProfile(
            NotificationUIManager::GetProfileID(profile_))) {
     notifications->insert(notification_id);
   }
   return true;
 }
-
-bool MessageCenterDisplayService::SupportsNotificationCenter() const {
-  return false;
-}