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

net/base/client_socket_pool.cc

 // 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.
 
 #include "net/base/client_socket_pool.h"
 
 #include "base/message_loop.h"
 #include "net/base/client_socket.h"
 #include "net/base/client_socket_handle.h"
 #include "net/base/net_errors.h"
@@ skipping 104 matching lines @@
   // NOTE: We cannot refer to the handle argument after this method returns.
   MessageLoop::current()->PostTask(FROM_HERE, NewRunnableMethod(
       this, &ClientSocketPool::DoReleaseSocket, handle->group_name_,
       handle->socket_));
 }
 
 void ClientSocketPool::CloseIdleSockets() {
   CleanupIdleSockets(true);
 }
 
+int ClientSocketPool::IdleSocketCountInGroup(
+    const std::string& group_name) const {
+  GroupMap::const_iterator i = group_map_.find(group_name);
+  DCHECK(i != group_map_.end());
+
+  return i->second.idle_sockets.size();
+}
+
 bool ClientSocketPool::IdleSocket::ShouldCleanup(base::TimeTicks now) const {
   bool timed_out = (now - start_time) >=
       base::TimeDelta::FromSeconds(kIdleTimeout);
   return timed_out || !(*ptr)->IsConnectedAndIdle();
 }
 
 void ClientSocketPool::CleanupIdleSockets(bool force) {
   if (idle_socket_count_ == 0)
     return;
 
@@ skipping 70 matching lines @@
   }
 
   // Delete group if no longer needed.
   if (group.active_socket_count == 0 && group.idle_sockets.empty()) {
     DCHECK(group.pending_requests.empty());
     group_map_.erase(i);
   }
 }
 
 }  // namespace net