Introduce ERR_NETWORK_CHANGED and allow URLFetcher to automatically retry on that error.

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 "net/base/net_export.h"
@@ skipping 191 matching lines @@
   static void NotifyObserversOfDNSChange();
 
   // Stores |config| in NetworkState and notifies observers.
   static void SetDnsConfig(const DnsConfig& config);
 
  private:
   friend class HostResolverImplDnsTest;
   friend class NetworkChangeNotifierAndroidTest;
   friend class NetworkChangeNotifierLinuxTest;
   friend class NetworkChangeNotifierWinTest;
+  friend class URLFetcherTest;
 
   class NetworkState;
 
   // Allows a second NetworkChangeNotifier to be created for unit testing, so
   // the test suite can create a MockNetworkChangeNotifier, but platform
   // specific NetworkChangeNotifiers can also be created for testing.  To use,
   // create an DisableForTest object, and then create the new
   // NetworkChangeNotifier object.  The NetworkChangeNotifier must be
   // destroyed before the DisableForTest object, as its destruction will restore
   // the original NetworkChangeNotifier.
@@ skipping 19 matching lines @@
 
   // A little-piggy-back observer that simply logs UMA histogram data.
   scoped_ptr<HistogramWatcher> histogram_watcher_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkChangeNotifier);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_NETWORK_CHANGE_NOTIFIER_H_