The Service Worker notificationclick event should carry a notification.

Source/modules/notifications/Notification.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 29 matching lines @@
 #include "public/platform/WebNotificationDelegate.h"
 #include "public/platform/WebNotificationPermission.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/RefCounted.h"
 
 namespace blink {
 
 class ExecutionContext;
 class NotificationOptions;
 class NotificationPermissionCallback;
+struct WebNotificationData;
 
 class Notification : public RefCountedGarbageCollectedWillBeGarbageCollectedFinalized<Notification>, public ActiveDOMObject, public EventTargetWithInlineData, public WebNotificationDelegate {
     DEFINE_EVENT_TARGET_REFCOUNTING_WILL_BE_REMOVED(RefCountedGarbageCollected<Notification>);
     DEFINE_WRAPPERTYPEINFO();
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(Notification);
 public:
+    // Used for JavaScript instantiations of the Notification object. Will automatically schedule for
+    // the notification to be displayed to the user.
     static Notification* create(ExecutionContext*, const String& title, const NotificationOptions&);
 
+    // Used for embedder-created Notification objects. Will initialize the Notification's state as showing.
+    static Notification* create(ExecutionContext*, const String& persistentId, const WebNotificationData&);
+
     virtual ~Notification();
 
     void close();
 
     DEFINE_ATTRIBUTE_EVENT_LISTENER(click);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(show);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(error);
     DEFINE_ATTRIBUTE_EVENT_LISTENER(close);
 
     // WebNotificationDelegate implementation.
@@ skipping 22 matching lines @@
     virtual bool dispatchEvent(PassRefPtrWillBeRawPtr<Event>) override final;
     virtual const AtomicString& interfaceName() const override;
 
     // ActiveDOMObject interface.
     virtual void stop() override;
     virtual bool hasPendingActivity() const override;
 
 private:
     Notification(const String& title, ExecutionContext*);
 
+    void scheduleShow();
+
     // Calling show() may start asynchronous operation. If this object has
     // a V8 wrapper, hasPendingActivity() prevents the wrapper from being
     // collected while m_state is Showing, and so this instance stays alive
     // until the operation completes. Otherwise, you need to hold a ref on this
     // instance until the operation completes.
     void show();
 
     void setDir(const String& dir) { m_dir = dir; }
     void setLang(const String& lang) { m_lang = lang; }
     void setBody(const String& body) { m_body = body; }
     void setIconUrl(KURL iconUrl) { m_iconUrl = iconUrl; }
     void setTag(const String& tag) { m_tag = tag; }
 
+    void setPersistentId(const String& persistentId) { m_persistentId = persistentId; }
+
 private:
     String m_title;
     String m_dir;
     String m_lang;
     String m_body;
     String m_tag;
 
     KURL m_iconUrl;
 
+    // Notifications can either be bound to the page, which means they're identified by
+    // their delegate, or persistent, which means they're identified by a persistent Id
+    // given to us by the embedder. This influences how we close the notification.
+    String m_persistentId;
+
     enum NotificationState {
         NotificationStateIdle,
         NotificationStateShowing,
         NotificationStateClosed
     };
 
+    // Only to be used by the Notification::create() method when notifications were created
+    // by the embedder rather than by Blink.
+    void setState(NotificationState state) { m_state = state; }
+
     NotificationState m_state;
 
     AsyncMethodRunner<Notification> m_asyncRunner;
 };
 
 } // namespace blink
 
 #endif // Notification_h