Revert 99677 (didn't help) - Revert 99666 (sync tests started failing on mac10.6:

net/base/network_change_notifier.h

 // Copyright (c) 2011 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_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/observer_list_threadsafe.h"
@@ skipping 32 matching lines @@
     // the unreliability of this signal.
     virtual void OnOnlineStateChanged(bool online) = 0;
 
    protected:
     OnlineStateObserver() {}
 
    private:
     DISALLOW_COPY_AND_ASSIGN(OnlineStateObserver);
   };
 
+  class NET_EXPORT DNSObserver {
+   public:
+    virtual ~DNSObserver() {}
+
+    // Will be called when the DNS resolver of the system may have changed.
+    // This is only used on Linux currently and watches /etc/resolv.conf
+    // and /etc/hosts
+    virtual void OnDNSChanged() = 0;
+
+   protected:
+    DNSObserver() {}
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(DNSObserver);
+  };
+
   virtual ~NetworkChangeNotifier();
 
   // See the description of NetworkChangeNotifier::IsOffline().
   // Implementations must be thread-safe. Implementations must also be
   // cheap as this could be called (repeatedly) from the IO thread.
   virtual bool IsCurrentlyOffline() const = 0;
 
   // Replaces the default class factory instance of NetworkChangeNotifier class.
   // The method will take over the ownership of |factory| object.
   static void SetFactory(NetworkChangeNotifierFactory* factory);
@@ skipping 19 matching lines @@
   // events, it merely rebroadcasts notifications when requested.
   static NetworkChangeNotifier* CreateMock();
 
   // Registers |observer| to receive notifications of network changes.  The
   // thread on which this is called is the thread on which |observer| will be
   // called back with notifications.  This is safe to call if Create() has not
   // been called (as long as it doesn't race the Create() call on another
   // thread), in which case it will simply do nothing.
   static void AddIPAddressObserver(IPAddressObserver* observer);
   static void AddOnlineStateObserver(OnlineStateObserver* observer);
+  static void AddDNSObserver(DNSObserver* observer);
 
   // Unregisters |observer| from receiving notifications.  This must be called
   // on the same thread on which AddObserver() was called.  Like AddObserver(),
   // this is safe to call if Create() has not been called (as long as it doesn't
   // race the Create() call on another thread), in which case it will simply do
   // nothing.  Technically, it's also safe to call after the notifier object has
   // been destroyed, if the call doesn't race the notifier's destruction, but
   // there's no reason to use the API in this risky way, so don't do it.
   static void RemoveIPAddressObserver(IPAddressObserver* observer);
   static void RemoveOnlineStateObserver(OnlineStateObserver* observer);
+  static void RemoveDNSObserver(DNSObserver* observer);
 
   // Allow unit tests to trigger notifications.
   static void NotifyObserversOfIPAddressChangeForTests() {
     NotifyObserversOfIPAddressChange();
   }
 
  protected:
   NetworkChangeNotifier();
 
   // Broadcasts a notification to all registered observers.  Note that this
   // happens asynchronously, even for observers on the current thread, even in
   // tests.
   static void NotifyObserversOfIPAddressChange();
   static void NotifyObserversOfOnlineStateChange();
+  static void NotifyObserversOfDNSChange();
 
  private:
   const scoped_refptr<ObserverListThreadSafe<IPAddressObserver> >
       ip_address_observer_list_;
   const scoped_refptr<ObserverListThreadSafe<OnlineStateObserver> >
       online_state_observer_list_;
+  const scoped_refptr<ObserverListThreadSafe<DNSObserver> >
+      resolver_state_observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifier);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_NETWORK_CHANGE_NOTIFIER_H_