[net] Adds AddressTrackerLinux which keeps track of interface addresses using rtnetlink.

net/base/network_change_notifier.h

 // Copyright (c) 2012 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 NET_BASE_NETWORK_CHANGE_NOTIFIER_H_
 #define NET_BASE_NETWORK_CHANGE_NOTIFIER_H_
 
 #include "base/basictypes.h"
 #include "base/observer_list_threadsafe.h"
 #include "base/synchronization/lock.h"
 #include "net/base/net_export.h"
 
 namespace net {
 
 class NetworkChangeNotifierFactory;
 
 namespace internal {
 class DnsConfigWatcher;
+
+#if defined(OS_LINUX)
+class AddressTrackerLinux;
+#endif
 }
 
 // NetworkChangeNotifier monitors the system for network changes, and notifies
 // registered observers of those events.  Observers may register on any thread,
 // and will be called back on the thread from which they registered.
 // NetworkChangeNotifiers are threadsafe, though they must be created and
 // destroyed on the same thread.
 class NET_EXPORT NetworkChangeNotifier {
  public:
   // Flags which are ORed together to form |detail| in OnDNSChanged.
@@ skipping 88 matching lines @@
   static NetworkChangeNotifier* Create();
 
   // Returns the connection type.
   // A return value of |CONNECTION_NONE| is a pretty strong indicator that the
   // user won't be able to connect to remote sites. However, another return
   // value doesn't imply that the user will be able to connect to remote sites;
   // even if some link is up, it is uncertain whether a particular connection
   // attempt to a particular remote site will be successful.
   static ConnectionType GetConnectionType();
 
+#if defined(OS_LINUX)
+  // Returns the AddressTrackerLinux if present.
+  static const internal::AddressTrackerLinux* GetAddressTracker();
+#endif
+
   // Convenience method to determine if the user is offline.
   // Returns true if there is currently no internet connection.
   //
   // A return value of |true| is a pretty strong indicator that the user
   // won't be able to connect to remote sites. However, a return value of
   // |false| is inconclusive; even if some link is up, it is uncertain
   // whether a particular connection attempt to a particular remote site
   // will be successfully.
   static bool IsOffline() {
     return GetConnectionType() == CONNECTION_NONE;
@@ skipping 77 matching lines @@
   //             http://crbug.com/116139
   base::Lock watching_dns_lock_;
   bool watching_dns_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifier);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_NETWORK_CHANGE_NOTIFIER_H_