Do not attempt to reuse active sockets after a socket pool flush (usually a network change).

net/socket/client_socket_pool.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 NET_SOCKET_CLIENT_SOCKET_POOL_H_
 #define NET_SOCKET_CLIENT_SOCKET_POOL_H_
 
 #include <deque>
 #include <map>
 #include <string>
@@ skipping 49 matching lines @@
   // same handle parameter must be passed to this method as was passed to the
   // RequestSocket call being cancelled.  The associated CompletionCallback is
   // not run.  However, for performance, we will let one ConnectJob complete
   // and go idle.
   virtual void CancelRequest(const std::string& group_name,
                              const ClientSocketHandle* handle) = 0;
 
   // Called to release a socket once the socket is no longer needed.  If the
   // socket still has an established connection, then it will be added to the
   // set of idle sockets to be used to satisfy future RequestSocket calls.
-  // Otherwise, the ClientSocket is destroyed.
+  // Otherwise, the ClientSocket is destroyed.  |id| is used to differentiate
+  // between updated versions of the same pool instance.  The pool's id will
+  // change when it flushes, so it can use this |id| to discard sockets with
+  // mismatched ids.
   virtual void ReleaseSocket(const std::string& group_name,
-                             ClientSocket* socket) = 0;
+                             ClientSocket* socket,
+                             int id) = 0;
+
+  // This flushes all state from the ClientSocketPool.  This means that all
+  // idle and connecting sockets are discarded.  Active sockets being
+  // held by ClientSocketPool clients will be discarded when released back to
+  // the pool.
+  virtual void Flush() = 0;
 
   // Called to close any idle connections held by the connection manager.
   virtual void CloseIdleSockets() = 0;
 
   // The total number of idle sockets in the pool.
   virtual int IdleSocketCount() const = 0;
 
   // The total number of idle sockets in a connection group.
   virtual int IdleSocketCountInGroup(const std::string& group_name) const = 0;
 
@@ skipping 33 matching lines @@
 
 // Provides an empty definition for CheckIsValidSocketParamsForPool() which
 // should be optimized out by the compiler.
 #define REGISTER_SOCKET_PARAMS_FOR_POOL(pool_type, socket_params)         \
 template<>                                                                \
 inline void CheckIsValidSocketParamsForPool<pool_type, socket_params>() {}
 
 }  // namespace net
 
 #endif  // NET_SOCKET_CLIENT_SOCKET_POOL_H_