[net] HostResolverImpl + DnsTransaction + DnsConfigService = Asynchronous DNS ready for experiments.

net/dns/dns_transaction.cc

Index: net/dns/dns_transaction.cc
diff --git a/net/dns/dns_transaction.cc b/net/dns/dns_transaction.cc
index 6cd02a33bd5b707945971bf300d3540d7a031c0d..222ee585310b946a52e627081885a0be955cfcb1 100644
--- a/net/dns/dns_transaction.cc
+++ b/net/dns/dns_transaction.cc
@@ -78,7 +78,7 @@ class ResponseParameters : public NetLog::EventParameters {
     DictionaryValue* dict = new DictionaryValue();
     dict->SetInteger("rcode", rcode_);
     dict->SetInteger("answer_count", answer_count_);
-    dict->Set("socket_source", source_.ToValue());
+    dict->Set("source_dependency", source_.ToValue());
     return dict;
   }
 
@@ -211,6 +211,8 @@ class DnsUDPAttempt {
       return rv;
 
     DCHECK(rv);
+    // TODO(szym): Consider making this check less aggressive.
+    // Other implementations simply ignore mismatched responses.
     if (!response_->InitParse(rv, *query_))
       return ERR_DNS_MALFORMED_RESPONSE;
     if (response_->flags() & dns_protocol::kFlagTC)
@@ -303,6 +305,10 @@ class DnsTransactionImpl : public DnsTransaction, public base::NonThreadSafe {
     return rv;
   }
 
+  virtual const BoundNetLog& net_log() const {

[mmenke, 2012/02/14 18:46:00]

nit:  OVERRIDE

+    return net_log_;
+  }
+
  private:
   // Prepares |qnames_| according to the DnsConfig.
   int PrepareSearch() {
@@ -387,7 +393,8 @@ class DnsTransactionImpl : public DnsTransaction, public base::NonThreadSafe {
     }
 
     net_log_.AddEvent(NetLog::TYPE_DNS_TRANSACTION_ATTEMPT, make_scoped_refptr(
-        new NetLogSourceParameter("socket_source", socket->NetLog().source())));
+        new NetLogSourceParameter("source_dependency",
+                                  socket->NetLog().source())));
 
     const DnsConfig& config = session_->config();