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

net/http/http_network_transaction.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/http/http_network_transaction.h"
 
 #include "base/scoped_ptr.h"
 #include "base/compiler_specific.h"
 #include "base/field_trial.h"
 #include "base/string_util.h"
@@ skipping 1015 matching lines @@
 
   base::TimeDelta host_resolution_and_tcp_connection_latency =
       base::Time::Now() - host_resolution_start_time_;
 
   UMA_HISTOGRAM_CLIPPED_TIMES(
       FieldTrial::MakeName(
           "Net.Dns_Resolution_And_TCP_Connection_Latency", "DnsImpact").data(),
       host_resolution_and_tcp_connection_latency,
       base::TimeDelta::FromMilliseconds(1), base::TimeDelta::FromMinutes(10),
       100);
+
+  UMA_HISTOGRAM_COUNTS_100(
+      FieldTrial::MakeName(
+          "Net.TCP_Connection_Idle_Sockets", "DnsImpact").data(),
+      session_->connection_pool()->IdleSocketCountInGroup(
+          connection_.group_name()));
 }
 
 void HttpNetworkTransaction::LogTransactionConnectedMetrics() const {
   base::TimeDelta total_duration = response_.response_time - start_time_;
 
   UMA_HISTOGRAM_CLIPPED_TIMES(
       FieldTrial::MakeName(
           "Net.Transaction_Connected_Under_10",
           "DnsImpact").data(),
       total_duration,
@@ skipping 624 matching lines @@
   if (target == HttpAuth::AUTH_PROXY) {
     auth_info->host = ASCIIToWide(proxy_info_.proxy_server().host_and_port());
   } else {
     DCHECK(target == HttpAuth::AUTH_SERVER);
     auth_info->host = ASCIIToWide(request_->url.host());
   }
   response_.auth_challenge = auth_info;
 }
 
 }  // namespace net