1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // This file describes a central switchboard for notifications that might 6 // happen in various parts of the application, and allows users to register 7 // observers for various classes of events that they're interested in. 8 9 #ifndef CONTENT_PUBLIC_BROWSER_NOTIFICATION_SERVICE_H_ 10 #define CONTENT_PUBLIC_BROWSER_NOTIFICATION_SERVICE_H_ 11 12 #include "content/common/content_export.h" 13 #include "content/public/browser/notification_details.h" 14 #include "content/public/browser/notification_source.h" 15 16 namespace content { 17 18 class CONTENT_EXPORT NotificationService { 19 public: 20 // Returns the NotificationService object for the current thread, or NULL if 21 // none. 22 static NotificationService* current(); 23 24 static NotificationService* Create(); 25 26 virtual ~NotificationService() {} 27 28 // Synchronously posts a notification to all interested observers. 29 // Source is a reference to a NotificationSource object representing 30 // the object originating the notification (can be 31 // NotificationService::AllSources(), in which case 32 // only observers interested in all sources will be notified). 33 // Details is a reference to an object containing additional data about 34 // the notification. If no additional data is needed, NoDetails() is used. 35 // There is no particular order in which the observers will be notified. 36 virtual void Notify(int type, 37 const NotificationSource& source, 38 const NotificationDetails& details) = 0; 39 40 // Returns a NotificationSource that represents all notification sources 41 // (for the purpose of registering an observer for events from all sources). 42 static Source<void> AllSources() { return Source<void>(NULL); } 43 44 // Returns the same value as AllSources(). This function has semantic 45 // differences to the programmer: We have checked that this AllSources() 46 // usage is safe in the face of multiple profiles. Objects that were 47 // singletons now will always have multiple instances, one per browser 48 // context. 49 // 50 // Some usage is safe, where the Source is checked to see if it's a member of 51 // a container before use. But, we want the number of AllSources() calls to 52 // drop to almost nothing, because most usages are not multiprofile safe and 53 // were done because it was easier to listen to everything. 54 static Source<void> AllBrowserContextsAndSources() { 55 return Source<void>(NULL); 56 } 57 58 // Returns a NotificationDetails object that represents a lack of details 59 // associated with a notification. (This is effectively a null pointer.) 60 static Details<void> NoDetails() { return Details<void>(NULL); } 61 }; 62 63 } // namespace content 64 65 #endif // CONTENT_PUBLIC_BROWSER_NOTIFICATION_SERVICE_H_ 66
