[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..d85b630e41d0263db20907ee7af406c11616f760 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());

[cbentzel, 2012/02/10 19:51:08]

Is this going to impact backwards compatibility of the JSON format? 

[szym, 2012/02/10 21:49:36]

These event parameters have been introduced recently http://crrev.com/119146 (2
weeks ago)
I added the "socket_source" parameter, but later learned that the automatic
linkage in chrome://net-internals will only work if the are named
"source_dependency".

     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)
@@ -387,7 +389,8 @@ 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();