[net/dns] Refactoring of job dispatch in HostResolverImpl in preparation for DnsTransactionFactory.

net/base/host_resolver.h

Index: net/base/host_resolver.h
diff --git a/net/base/host_resolver.h b/net/base/host_resolver.h
index a5966103d6a24495a18733be4dd5b09fbe501d10..c4f33582df0220238ac538d4fe8a5be8f13cb9d7 100644
--- a/net/base/host_resolver.h
+++ b/net/base/host_resolver.h
@@ -182,6 +182,12 @@ NET_EXPORT HostResolver* CreateSystemHostResolver(
     size_t max_retry_attempts,
     NetLog* net_log);
 
+// As above, but the created HostResolver does not use a cache.
+NET_EXPORT HostResolver* CreateNonCachingSystemHostResolver(
+    size_t max_concurrent_resolves,
+    size_t max_retry_attempts,
+    NetLog* net_log);
+
 // Creates a HostResolver implementation that sends actual DNS queries to
 // the specified DNS server and parses response and returns results.
 NET_EXPORT HostResolver* CreateAsyncHostResolver(size_t max_concurrent_resolves,