[Not for review] Add TRACE_EVENTs and chrome://flags for preconnect

net/dns/dns_response.cc

 // Copyright (c) 2012 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/dns/dns_response.h"
 
 #include <limits>
 
 #include "base/big_endian.h"
 #include "base/strings/string_util.h"
 #include "base/sys_byteorder.h"
+#include "base/trace_event/trace_event.h"
 #include "net/base/address_list.h"
 #include "net/base/io_buffer.h"
 #include "net/base/ip_address.h"
 #include "net/base/net_errors.h"
 #include "net/dns/dns_protocol.h"
 #include "net/dns/dns_query.h"
 #include "net/dns/dns_util.h"
 
 namespace net {
 
@@ skipping 249 matching lines @@
   return parser_;
 }
 
 const dns_protocol::Header* DnsResponse::header() const {
   return reinterpret_cast<const dns_protocol::Header*>(io_buffer_->data());
 }
 
 DnsResponse::Result DnsResponse::ParseToAddressList(
     AddressList* addr_list,
     base::TimeDelta* ttl) const {
+  TRACE_EVENT0("net", "DnsResponse::ParseToAddressList");
   DCHECK(IsValid());
   // DnsTransaction already verified that |response| matches the issued query.
   // We still need to determine if there is a valid chain of CNAMEs from the
   // query name to the RR owner name.
   // We err on the side of caution with the assumption that if we are too picky,
   // we can always fall back to the system getaddrinfo.
 
   // Expected owner of record. No trailing dot.
   std::string expected_name = GetDottedName();
 
@@ skipping 45 matching lines @@
 
   // getcanonname in eglibc returns the first owner name of an A or AAAA RR.
   // If the response passed all the checks so far, then |expected_name| is it.
   *addr_list = AddressList::CreateFromIPAddressList(ip_addresses,
                                                     expected_name);
   *ttl = base::TimeDelta::FromSeconds(ttl_sec);
   return DNS_PARSE_OK;
 }
 
 }  // namespace net