diff -r 000000000000 -r 6474c204b198 ipc/chromium/src/chrome/common/notification_service.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ipc/chromium/src/chrome/common/notification_service.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,100 @@
+// Copyright (c) 2006-2008 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.
+
+// This file describes a central switchboard for notifications that might
+// happen in various parts of the application, and allows users to register
+// observers for various classes of events that they're interested in.
+
+#ifndef CHROME_COMMON_NOTIFICATION_SERVICE_H_
+#define CHROME_COMMON_NOTIFICATION_SERVICE_H_
+
+#include <map>
+
+#include "base/observer_list.h"
+#include "chrome/common/notification_details.h"
+#include "chrome/common/notification_observer.h"
+#include "chrome/common/notification_source.h"
+#include "chrome/common/notification_type.h"
+
+class NotificationObserver;
+
+class NotificationService {
+ public:
+  // Returns the NotificationService object for the current thread, or NULL if
+  // none.
+  static NotificationService* current();
+
+  // Normally instantiated when the thread is created.  Not all threads have
+  // a NotificationService.  Only one instance should be created per thread.
+  NotificationService();
+  ~NotificationService();
+
+  // Registers a NotificationObserver to be called whenever a matching
+  // notification is posted.  Observer is a pointer to an object subclassing
+  // NotificationObserver to be notified when an event matching the other two
+  // parameters is posted to this service.  Type is the type of events to
+  // be notified about (or NOTIFY_ALL to receive events of all types).
+  // Source is a NotificationSource object (created using
+  // "Source<classname>(pointer)"), if this observer only wants to
+  // receive events from that object, or NotificationService::AllSources()
+  // to receive events from all sources.
+  //
+  // A given observer can be registered only once for each combination of
+  // type and source.  If the same object is registered more than once,
+  // it must be removed for each of those combinations of type and source later.
+  //
+  // The caller retains ownership of the object pointed to by observer.
+  void AddObserver(NotificationObserver* observer,
+                   NotificationType type, const NotificationSource& source);
+
+  // Removes the object pointed to by observer from receiving notifications
+  // that match type and source.  If no object matching the parameters is
+  // currently registered, this method is a no-op.
+  void RemoveObserver(NotificationObserver* observer,
+                      NotificationType type, const NotificationSource& source);
+
+  // Synchronously posts a notification to all interested observers.
+  // Source is a reference to a NotificationSource object representing
+  // the object originating the notification (can be
+  // NotificationService::AllSources(), in which case
+  // only observers interested in all sources will be notified).
+  // Details is a reference to an object containing additional data about
+  // the notification.  If no additional data is needed, NoDetails() is used.
+  // There is no particular order in which the observers will be notified.
+  void Notify(NotificationType type,
+              const NotificationSource& source,
+              const NotificationDetails& details);
+
+  // Returns a NotificationSource that represents all notification sources
+  // (for the purpose of registering an observer for events from all sources).
+  static Source<void> AllSources() { return Source<void>(NULL); }
+
+  // Returns a NotificationDetails object that represents a lack of details
+  // associated with a notification.  (This is effectively a null pointer.)
+  static Details<void> NoDetails() { return Details<void>(NULL); }
+
+ private:
+  typedef base::ObserverList<NotificationObserver> NotificationObserverList;
+  typedef std::map<uintptr_t, NotificationObserverList*> NotificationSourceMap;
+
+  // Convenience function to determine whether a source has a
+  // NotificationObserverList in the given map;
+  static bool HasKey(const NotificationSourceMap& map,
+                     const NotificationSource& source);
+
+  // Keeps track of the observers for each type of notification.
+  // Until we get a prohibitively large number of notification types,
+  // a simple array is probably the fastest way to dispatch.
+  NotificationSourceMap observers_[NotificationType::NOTIFICATION_TYPE_COUNT];
+
+#ifndef NDEBUG
+  // Used to check to see that AddObserver and RemoveObserver calls are
+  // balanced.
+  int observer_counts_[NotificationType::NOTIFICATION_TYPE_COUNT];
+#endif
+
+  DISALLOW_COPY_AND_ASSIGN(NotificationService);
+};
+
+#endif  // CHROME_COMMON_NOTIFICATION_SERVICE_H_