net: plumb DnsRRResolver from IOThread to HttpNetworkSession.

net/url_request/url_request_context.h

Index: net/url_request/url_request_context.h
diff --git a/net/url_request/url_request_context.h b/net/url_request/url_request_context.h
index 5198fa37e1a64ebfcd001d2f0096ca2792934bd0..96de77d813057ccd6876d021a377ff9591f2ca80 100644
--- a/net/url_request/url_request_context.h
+++ b/net/url_request/url_request_context.h
@@ -22,6 +22,7 @@
 namespace net {
 class CookiePolicy;
 class CookieStore;
+class DnsRRResolver;
 class FtpTransactionFactory;
 class HostResolver;
 class HttpAuthHandlerFactory;
@@ -46,6 +47,10 @@ class URLRequestContext
     return host_resolver_;
   }
 
+  net::DnsRRResolver* dnsrr_resolver() const {
+    return dnsrr_resolver_;
+  }
+
   // Get the proxy service for this context.
   net::ProxyService* proxy_service() const {
     return proxy_service_;
@@ -113,6 +118,7 @@ class URLRequestContext
   // subclasses.
   net::NetLog* net_log_;
   net::HostResolver* host_resolver_;
+  net::DnsRRResolver* dnsrr_resolver_;
   scoped_refptr<net::ProxyService> proxy_service_;
   scoped_refptr<net::SSLConfigService> ssl_config_service_;
   net::HttpTransactionFactory* http_transaction_factory_;