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

net/dns/dns_transaction.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_transaction.h"
 
 #include <deque>
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/big_endian.h"
 #include "base/bind.h"
 #include "base/location.h"
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/profiler/scoped_tracker.h"
 #include "base/rand_util.h"
 #include "base/single_thread_task_runner.h"
 #include "base/stl_util.h"
 #include "base/strings/string_piece.h"
 #include "base/threading/non_thread_safe.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/timer/timer.h"
+#include "base/trace_event/trace_event.h"
 #include "base/values.h"
 #include "net/base/completion_callback.h"
 #include "net/base/io_buffer.h"
 #include "net/base/ip_address.h"
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_errors.h"
 #include "net/dns/dns_protocol.h"
 #include "net/dns/dns_query.h"
 #include "net/dns/dns_response.h"
 #include "net/dns/dns_session.h"
@@ skipping 238 matching lines @@
     // TODO(szym): Extract TTL for NXDOMAIN results. http://crbug.com/115051
     if (response_->rcode() == dns_protocol::kRcodeNXDOMAIN)
       return ERR_NAME_NOT_RESOLVED;
     if (response_->rcode() != dns_protocol::kRcodeNOERROR)
       return ERR_DNS_SERVER_FAILED;
 
     return OK;
   }
 
   void OnIOComplete(int rv) {
+    TRACE_EVENT1("net", "DnsUDPAttempt::OnIOComplete", "qname",
+                 query_->qname().as_string());
     rv = DoLoop(rv);
     if (rv != ERR_IO_PENDING)
       callback_.Run(rv);
   }
 
   State next_state_;
   bool received_malformed_response_;
   base::TimeTicks start_time_;
 
   std::unique_ptr<DnsSession::SocketLease> socket_lease_;
@@ skipping 497 matching lines @@
       // Custom timeout for TCP attempt.
       base::TimeDelta timeout = timer_.GetCurrentDelay() * 2;
       timer_.Start(FROM_HERE, timeout, this, &DnsTransactionImpl::OnTimeout);
     }
     return AttemptResult(rv, attempt);
   }
 
   // Begins query for the current name. Makes the first attempt.
   AttemptResult StartQuery() {
     std::string dotted_qname = DNSDomainToString(qnames_.front());
+    TRACE_EVENT1("net", "DnsTransactionImpl::StartQuery", "dotted_qname",
+                 dotted_qname);
     net_log_.BeginEvent(NetLogEventType::DNS_TRANSACTION_QUERY,
                         NetLog::StringCallback("qname", &dotted_qname));
 
     first_server_index_ = session_->NextFirstServerIndex();
     RecordLostPacketsIfAny();
     attempts_.clear();
     had_tcp_attempt_ = false;
     return MakeAttempt();
   }
 
@@ skipping 185 matching lines @@
 }  // namespace
 
 // static
 std::unique_ptr<DnsTransactionFactory> DnsTransactionFactory::CreateFactory(
     DnsSession* session) {
   return std::unique_ptr<DnsTransactionFactory>(
       new DnsTransactionFactoryImpl(session));
 }
 
 }  // namespace net