[net] Add Net.UnspecResolvedIPv6 to measure if getaddrinfo resolves IPv6 addresses.

net/base/host_resolver_impl.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/base/host_resolver_impl.h"
 
 #if defined(OS_WIN)
 #include <Winsock2.h>
 #elif defined(OS_POSIX)
 #include <netdb.h>
@@ skipping 1387 matching lines @@
     // call OnProcTaskComplete, for example, on synchronous failure.
     proc_task_->Start();
   }
 
   // Called by ProcTask when it completes.
   void OnProcTaskComplete(base::TimeTicks start_time,
                           int net_error,
                           const AddressList& addr_list) {
     DCHECK(is_proc_running());
 
+    if (!resolver_->resolved_known_ipv6_hostname_ &&
+        net_error == OK &&
+        key_.address_family == ADDRESS_FAMILY_UNSPECIFIED) {
+      if (key_.hostname == "www.google.com") {
+        resolver_->resolved_known_ipv6_hostname_ = true;
+        bool got_ipv6_address = false;
+        for (size_t i = 0; i < addr_list.size(); ++i) {
+          if (addr_list[i].GetFamily() == ADDRESS_FAMILY_IPV6)
+            got_ipv6_address = true;
+        }
+        UMA_HISTOGRAM_BOOLEAN("Net.UnspecResolvedIPv6", got_ipv6_address);
+      }
+    }
+
     if (dns_task_error_ != OK) {
       base::TimeDelta duration = base::TimeTicks::Now() - start_time;
       if (net_error == OK) {
         DNS_HISTOGRAM("AsyncDNS.FallbackSuccess", duration);
         if ((dns_task_error_ == ERR_NAME_NOT_RESOLVED) &&
             ResemblesNetBIOSName(key_.hostname)) {
           UmaAsyncDnsResolveStatus(RESOLVE_STATUS_SUSPECT_NETBIOS);
         } else {
           UmaAsyncDnsResolveStatus(RESOLVE_STATUS_PROC_SUCCESS);
         }
@@ skipping 234 matching lines @@
 
 HostResolverImpl::HostResolverImpl(
     scoped_ptr<HostCache> cache,
     const PrioritizedDispatcher::Limits& job_limits,
     const ProcTaskParams& proc_params,
     NetLog* net_log)
     : cache_(cache.Pass()),
       dispatcher_(job_limits),
       max_queued_jobs_(job_limits.total_jobs * 100u),
       proc_params_(proc_params),
+      net_log_(net_log),
       default_address_family_(ADDRESS_FAMILY_UNSPECIFIED),
       weak_ptr_factory_(this),
       probe_weak_ptr_factory_(this),
       received_dns_config_(false),
       num_dns_failures_(0),
       ipv6_probe_monitoring_(false),
-      additional_resolver_flags_(0),
-      net_log_(net_log) {
+      resolved_known_ipv6_hostname_(false),
+      additional_resolver_flags_(0) {
 
   DCHECK_GE(dispatcher_.num_priorities(), static_cast<size_t>(NUM_PRIORITIES));
 
   // Maximum of 4 retry attempts for host resolution.
   static const size_t kDefaultMaxRetryAttempts = 4u;
 
   if (proc_params_.max_retry_attempts == HostResolver::kDefaultRetryAttempts)
     proc_params_.max_retry_attempts = kDefaultMaxRetryAttempts;
 
 #if defined(OS_WIN)
@@ skipping 372 matching lines @@
 
   for (JobMap::iterator it = jobs_.begin(); self && it != jobs_.end(); ) {
     Job* job = it->second;
     ++it;
     // This could remove |job| from |jobs_|, but iterator will remain valid.
     job->ServeFromHosts();
   }
 }
 
 void HostResolverImpl::OnIPAddressChanged() {
+  resolved_known_ipv6_hostname_ = false;
   // Abandon all ProbeJobs.
   probe_weak_ptr_factory_.InvalidateWeakPtrs();
   if (cache_.get())
     cache_->clear();
   if (ipv6_probe_monitoring_)
     new IPv6ProbeJob(probe_weak_ptr_factory_.GetWeakPtr(), net_log_);
 #if defined(OS_POSIX) && !defined(OS_MACOSX)
   new LoopbackProbeJob(probe_weak_ptr_factory_.GetWeakPtr());
 #endif
   AbortAllInProgressJobs();
@@ skipping 83 matching lines @@
   }
   DnsConfig dns_config;
   NetworkChangeNotifier::GetDnsConfig(&dns_config);
   dns_client_->SetConfig(dns_config);
   num_dns_failures_ = 0;
   if (dns_config.IsValid())
     UMA_HISTOGRAM_BOOLEAN("AsyncDNS.DnsClientEnabled", true);
 }
 
 }  // namespace net