Add a new histogram for tracking how much time is spent resolving hosts

net/quic/quic_stream_factory.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/quic/quic_stream_factory.h"
 
 #include <set>
 
 #include "base/cpu.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 193 matching lines @@
   SingleRequestHostResolver host_resolver_;
   QuicServerId server_id_;
   bool is_post_;
   bool was_alternate_protocol_recently_broken_;
   scoped_ptr<QuicServerInfo> server_info_;
   const BoundNetLog net_log_;
   QuicClientSession* session_;
   CompletionCallback callback_;
   AddressList address_list_;
   base::TimeTicks disk_cache_load_start_time_;
+  base::TimeTicks dns_resolution_start_time_;
   base::WeakPtrFactory<Job> weak_factory_;
   DISALLOW_COPY_AND_ASSIGN(Job);
 };
 
 QuicStreamFactory::Job::Job(QuicStreamFactory* factory,
                             HostResolver* host_resolver,
                             const HostPortPair& host_port_pair,
                             bool is_https,
                             bool was_alternate_protocol_recently_broken,
                             PrivacyMode privacy_mode,
@@ skipping 84 matching lines @@
 }
 
 int QuicStreamFactory::Job::DoResolveHost() {
   // Start loading the data now, and wait for it after we resolve the host.
   if (server_info_) {
     disk_cache_load_start_time_ = base::TimeTicks::Now();
     server_info_->Start();
   }
 
   io_state_ = STATE_RESOLVE_HOST_COMPLETE;
+  dns_resolution_start_time_ = base::TimeTicks::Now();
   return host_resolver_.Resolve(
       HostResolver::RequestInfo(server_id_.host_port_pair()),
       DEFAULT_PRIORITY,
       &address_list_,
       base::Bind(&QuicStreamFactory::Job::OnIOComplete,
                  weak_factory_.GetWeakPtr()),
       net_log_);
 }
 
 int QuicStreamFactory::Job::DoResolveHostComplete(int rv) {
+  UMA_HISTOGRAM_TIMES("Net.QuicSession.HostResolutionTime",
+                      base::TimeTicks::Now() - dns_resolution_start_time_);
   if (rv != OK)
     return rv;
 
   DCHECK(!factory_->HasActiveSession(server_id_));
 
   // Inform the factory of this resolution, which will set up
   // a session alias, if possible.
   if (factory_->OnResolution(server_id_, address_list_)) {
     return OK;
   }
@@ skipping 638 matching lines @@
   http_server_properties_->ClearAlternateProtocol(server);
   http_server_properties_->SetAlternateProtocol(
       server, alternate.port, alternate.protocol, 1);
   DCHECK_EQ(QUIC,
             http_server_properties_->GetAlternateProtocol(server).protocol);
   DCHECK(http_server_properties_->WasAlternateProtocolRecentlyBroken(
       server));
 }
 
 }  // namespace net