RE-add the ability to delete notification ids unknown by the display service.

content/browser/notifications/platform_notification_context_impl.cc

Index: content/browser/notifications/platform_notification_context_impl.cc
diff --git a/content/browser/notifications/platform_notification_context_impl.cc b/content/browser/notifications/platform_notification_context_impl.cc
index 8ef474c619dccc40b4cef826bda96630b8e02806..8a15289d8aac51406bc6db6714058e99d5dc3317 100644
--- a/content/browser/notifications/platform_notification_context_impl.cc
+++ b/content/browser/notifications/platform_notification_context_impl.cc
@@ -281,10 +281,10 @@ void PlatformNotificationContextImpl::
   UMA_HISTOGRAM_ENUMERATION("Notifications.Database.ReadForServiceWorkerResult",
                             status, NotificationDatabase::STATUS_COUNT);
 
+  std::vector<std::string> obsolete_notifications;
+
   if (status == NotificationDatabase::STATUS_OK) {
     if (supports_synchronization) {
-      // Filter out notifications that are not actually on display anymore.
-      // TODO(miguelg) synchronize the database if there are inconsistencies.
       for (auto it = notification_datas.begin();
            it != notification_datas.end();) {
         // The database is only used for persistent notifications.
@@ -293,6 +293,7 @@ void PlatformNotificationContextImpl::
         if (displayed_notifications->count(it->notification_id)) {
           ++it;
         } else {
+          obsolete_notifications.push_back(it->notification_id);
           it = notification_datas.erase(it);
         }
       }
@@ -301,6 +302,10 @@ void PlatformNotificationContextImpl::
     BrowserThread::PostTask(
         BrowserThread::IO, FROM_HERE,
         base::Bind(callback, true /* success */, notification_datas));
+
+    // Remove notifications that are not actually on display anymore.
+    for (const auto& it : obsolete_notifications)
+      database_->DeleteNotificationData(it, origin);
     return;
   }