Massively simplify the NetworkChangeNotifier infrastructure:...

chrome/common/net/network_change_observer_proxy.h

-// Copyright (c) 2010 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.
-
-#ifndef CHROME_COMMON_NET_NETWORK_CHANGE_OBSERVER_PROXY_H_
-#define CHROME_COMMON_NET_NETWORK_CHANGE_OBSERVER_PROXY_H_
-
-// NetworkChangeObserverProxy is a class that listens to a
-// NetworkChangeNotifier on one thread (the source thread, which is
-// usually the Chrome IO thread) and emits events to a target observer
-// on another thread (the target thread).
-//
-// How to use:
-//
-// In the target thread, create the observer proxy:
-//
-//   NetworkChangeNotifierThread* source_thread = ...;
-//   NetworkChangeObserverProxy* proxy =
-//       new NetworkChangeObserverProxy(source_thread,
-//                                      MessageLoop::current());
-//
-// Both source_thread and its owned NetworkChangeNotifier must be
-// guaranteed to outlive the target (current) thread.
-//
-// Then, attach the target observer:
-//
-//   proxy->Attach(target_observer);
-//
-// target_observer will then begin to receive events on the target
-// thread.
-//
-// If you call Attach(), you *must* call Detach() before releasing:
-//
-//   proxy->Detach();
-//   proxy->Release();  // omit if proxy is a scoped_refptr
-//   proxy = NULL;
-//
-// The proxy may be destroyed on either the source or the target
-// thread (depending on which one ends up holding the last reference).
-
-#include "base/basictypes.h"
-#include "base/message_loop.h"
-#include "base/ref_counted.h"
-#include "net/base/network_change_notifier.h"
-
-namespace chrome_common_net {
-
-class NetworkChangeNotifierThread;
-
-// TODO(akalin): Remove use of private inheritance.
-class NetworkChangeObserverProxy
-    : public base::RefCountedThreadSafe<NetworkChangeObserverProxy>,
-      private net::NetworkChangeNotifier::Observer {
- public:
-  // All public methods (including the constructor) must be called on
-  // the target thread.
-
-  // Does not take ownership of any arguments.
-  NetworkChangeObserverProxy(
-      const NetworkChangeNotifierThread* source_thread,
-      MessageLoop* target_message_loop);
-
-  // After this method is called, |target_observer| will start
-  // receiving events on the target thread.  Once called, Detach()
-  // must be called before releasing and you cannot call Attach()
-  // again until you have done so.  Does not take ownership of
-  // |target_observer|.
-  void Attach(net::NetworkChangeNotifier::Observer* target_observer);
-
-  // After this method is called, the target observer will stop
-  // receiving events.  You can call Attach() again after this method
-  // is called.
-  void Detach();
-
- protected:
-  // May be called on either the source or the target thread.  Marked
-  // protected instead of private so that this class can be subclassed
-  // for unit tests.
-  virtual ~NetworkChangeObserverProxy();
-
- private:
-  friend class base::RefCountedThreadSafe<NetworkChangeObserverProxy>;
-
-  // Adds ourselves as an observer of
-  // |source_network_change_notifier_|.  Must be called on the source
-  // thread.
-  void Observe();
-
-  // Removes ourselves as an observer of
-  // |source_network_change_notifier_|.  Must be called on the source
-  // thread.
-  void Unobserve();
-
-  // net::NetworkChangeNotifier::Observer implementation.
-  //
-  // Called on the source thread.  Posts
-  // TargetObserverOnIPAddressChanged() on the target thread.
-  virtual void OnIPAddressChanged();
-
-  // Called on the target thread.  Invokes OnIPAddressChanged() on
-  // |target_observer_|.
-  void TargetObserverOnIPAddressChanged();
-
-  const NetworkChangeNotifierThread* source_thread_;
-  MessageLoop* const target_message_loop_;
-  // |target_observer_| is used only by the target thread.
-  net::NetworkChangeNotifier::Observer* target_observer_;
-
-  DISALLOW_COPY_AND_ASSIGN(NetworkChangeObserverProxy);
-};
-
-}  // namespace chrome_common_net
-
-#endif  // CHROME_COMMON_NET_NETWORK_CHANGE_OBSERVER_PROXY_H_