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

net/socket/client_socket_pool_base.h

Index: net/socket/client_socket_pool_base.h
diff --git a/net/socket/client_socket_pool_base.h b/net/socket/client_socket_pool_base.h
index e35ab29fca11f767943d2ff2a676ac216e3921b4..3026570ab09bbe17ed7ee546620c8e7845686cbf 100644
--- a/net/socket/client_socket_pool_base.h
+++ b/net/socket/client_socket_pool_base.h
@@ -243,7 +243,7 @@ class NET_EXPORT_PRIVATE ClientSocketPoolBaseHelper
                      int id);
 
   // See ClientSocketPool::Flush for documentation on this function.
-  void Flush();
+  void Flush(int error);
 
   // See ClientSocketPool::IsStalled for documentation on this function.
   bool IsStalled() const;
@@ -505,9 +505,9 @@ class NET_EXPORT_PRIVATE ClientSocketPoolBaseHelper
   // groups if they are no longer needed.
   void CancelAllConnectJobs();
 
-  // Iterates through |group_map_|, posting ERR_ABORTED callbacks for all
+  // Iterates through |group_map_|, posting |error| callbacks for all
   // requests, and then deleting groups if they are no longer needed.
-  void AbortAllRequests();
+  void AbortAllRequests(int error);
 
   // Returns true if we can't create any more sockets due to the total limit.
   bool ReachedMaxSocketsLimit() const;
@@ -708,7 +708,7 @@ class ClientSocketPoolBase {
     return helper_.ReleaseSocket(group_name, socket, id);
   }
 
-  void Flush() { helper_.Flush(); }
+  void Flush() { helper_.Flush(ERR_ABORTED); }
 
   bool IsStalled() const { return helper_.IsStalled(); }