Add a histogram to measure the number of idle sockets when a TCP connection is established.

net/base/client_socket_pool.h

 // Copyright (c) 2006-2008 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_CLIENT_SOCKET_POOL_H_
 #define NET_BASE_CLIENT_SOCKET_POOL_H_
 
 #include <deque>
 #include <map>
 #include <string>
@@ skipping 55 matching lines @@
   void ReleaseSocket(ClientSocketHandle* handle);
 
   // Called to close any idle connections held by the connection manager.
   void CloseIdleSockets();
 
   // The total number of idle sockets in the pool.
   int idle_socket_count() const {
     return idle_socket_count_;
   }
 
+  // The total number of idle sockets in a connection group.
+  int IdleSocketCountInGroup(const std::string& group_name) const;
+
  private:
   friend class base::RefCounted<ClientSocketPool>;
 
   typedef scoped_ptr<ClientSocket> ClientSocketPtr;
 
   // A Request is allocated per call to RequestSocket that results in
   // ERR_IO_PENDING.
   struct Request {
     ClientSocketHandle* handle;
     CompletionCallback* callback;
@@ skipping 61 matching lines @@
 
   // The maximum number of sockets kept per group.
   int max_sockets_per_group_;
 
   DISALLOW_COPY_AND_ASSIGN(ClientSocketPool);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_CLIENT_SOCKET_POOL_H_