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      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 #ifndef CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_
      6 #define CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_
      7 
      8 #include <vector>
      9 
     10 #include "base/basictypes.h"
     11 #include "base/threading/non_thread_safe.h"
     12 #include "content/common/content_export.h"
     13 
     14 namespace content {
     15 
     16 class NotificationObserver;
     17 class NotificationSource;
     18 
     19 // Aids in registering for notifications and ensures that all registered
     20 // notifications are unregistered when the class is destroyed.
     21 //
     22 // The intended use is that you make a NotificationRegistrar member in your
     23 // class and use it to register your notifications instead of going through the
     24 // notification service directly. It will automatically unregister them for
     25 // you.
     26 class CONTENT_EXPORT NotificationRegistrar :
     27     NON_EXPORTED_BASE(public base::NonThreadSafe) {
     28  public:
     29   // This class must not be derived from (we don't have a virtual destructor so
     30   // it won't work). Instead, use it as a member in your class.
     31   NotificationRegistrar();
     32   ~NotificationRegistrar();
     33 
     34   // Wrappers around NotificationService::[Add|Remove]Observer.
     35   void Add(NotificationObserver* observer,
     36            int type,
     37            const NotificationSource& source);
     38   void Remove(NotificationObserver* observer,
     39               int type,
     40               const NotificationSource& source);
     41 
     42   // Unregisters all notifications.
     43   void RemoveAll();
     44 
     45   // Returns true if no notifications are registered.
     46   bool IsEmpty() const;
     47 
     48   // Returns true if there is already a registered notification with the
     49   // specified details.
     50   bool IsRegistered(NotificationObserver* observer,
     51                     int type,
     52                     const NotificationSource& source);
     53 
     54  private:
     55   struct Record;
     56 
     57   // We keep registered notifications in a simple vector. This means we'll do
     58   // brute-force searches when removing them individually, but individual
     59   // removal is uncommon, and there will typically only be a couple of
     60   // notifications anyway.
     61   typedef std::vector<Record> RecordVector;
     62 
     63   // Lists all notifications we're currently registered for.
     64   RecordVector registered_;
     65 
     66   DISALLOW_COPY_AND_ASSIGN(NotificationRegistrar);
     67 };
     68 
     69 }  // namespace content
     70 
     71 #endif  // CONTENT_PUBLIC_BROWSER_NOTIFICATION_REGISTRAR_H_
     72