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

net/base/host_resolver.h

 // Copyright (c) 2011 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.
 
 #ifndef NET_BASE_HOST_RESOLVER_H_
 #define NET_BASE_HOST_RESOLVER_H_
 #pragma once
 
 #include <string>
 
@@ skipping 164 matching lines @@
 // run in parallel. Pass HostResolver::kDefaultParallelism to choose a
 // default value.
 // |max_retry_attempts| is the maximum number of times we will retry for host
 // resolution. Pass HostResolver::kDefaultRetryAttempts to choose a default
 // value.
 NET_EXPORT HostResolver* CreateSystemHostResolver(
     size_t max_concurrent_resolves,
     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,
                                                  const IPAddressNumber& dns_ip,
                                                  NetLog* net_log);
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_H_