Remove persistent notifications from the database when they close.

chrome/browser/notifications/persistent_notification_delegate.cc

 // Copyright 2014 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/persistent_notification_delegate.h"
 
 #include "base/bind.h"
 #include "base/guid.h"
 #include "chrome/browser/notifications/platform_notification_service_impl.h"
 #include "content/public/common/persistent_notification_status.h"
 
 PersistentNotificationDelegate::PersistentNotificationDelegate(
     content::BrowserContext* browser_context,
     int64_t persistent_notification_id,
     const GURL& origin)
     : browser_context_(browser_context),
       persistent_notification_id_(persistent_notification_id),
       origin_(origin),
       id_(base::GenerateGUID()) {}
 
 PersistentNotificationDelegate::~PersistentNotificationDelegate() {}
 
 void PersistentNotificationDelegate::Display() {}
 
-void PersistentNotificationDelegate::Close(bool by_user) {}
+void PersistentNotificationDelegate::Close(bool by_user) {
+  PlatformNotificationServiceImpl::GetInstance()->OnPersistentNotificationClose(
+      browser_context_,
+      persistent_notification_id_,
+      origin_);
+}
 
 void PersistentNotificationDelegate::Click() {
   PlatformNotificationServiceImpl::GetInstance()->OnPersistentNotificationClick(
       browser_context_,
       persistent_notification_id_,
       origin_);
 }
 
 std::string PersistentNotificationDelegate::id() const {
   return id_;
 }