Initial support for built-in DNS resolver/cache.

net/base/host_resolver_impl.cc

 // Copyright (c) 2010 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.
 
 #include "net/base/host_resolver_impl.h"
 
 #if defined(OS_WIN)
 #include <Winsock2.h>
 #elif defined(OS_POSIX)
 #include <netdb.h>
@@ skipping 54 matching lines @@
       kMaxHostCacheEntries,
       base::TimeDelta::FromMinutes(1),
       base::TimeDelta::FromSeconds(0));  // Disable caching of failed DNS.
 
   return cache;
 }
 
 }  // anonymous namespace
 
 HostResolver* CreateSystemHostResolver(size_t max_concurrent_resolves,
+                                       HostResolverProc* resolver_proc,

[eroman, 2011/01/10 20:13:45]

This change doesn't make sense to me.

The "CreateSystemHostResolver()" is supposed to be creating a host resolver that
uses the underlying system's getaddrinfo().

However if we pass in a custom HostResolverProc then that is not the case.

I don't think we should be adding an extra parameter to this function which will
always be NULL. Rather the one location(s) which want to create their custom
non-system host resolver should just call:

   new HostResolverImpl(resolver_proc, ....)

In fact for the feature you ware working on I think it should be implemented as
a separate HostResolver subclass alltogether, and not use a custom
HostResolverProc.

(The HostResolverProc were really just a feature for unit-tests, in order to
mock out the system dependency).

                                        NetLog* net_log) {
   // Maximum of 50 concurrent threads.
   // TODO(eroman): Adjust this, do some A/B experiments.
   static const size_t kDefaultMaxJobs = 50u;
 
   if (max_concurrent_resolves == HostResolver::kDefaultParallelism)
     max_concurrent_resolves = kDefaultMaxJobs;
 
   HostResolverImpl* resolver =
-      new HostResolverImpl(NULL, CreateDefaultCache(),
+      new HostResolverImpl(resolver_proc, CreateDefaultCache(),
                            max_concurrent_resolves, net_log);
 
   return resolver;
 }
 
 static int ResolveAddrInfo(HostResolverProc* resolver_proc,
                            const std::string& host,
                            AddressFamily address_family,
                            HostResolverFlags host_resolver_flags,
                            AddressList* out,
@@ skipping 1346 matching lines @@
     job_pools_[i]->ResetNumOutstandingJobs();
   JobMap jobs;
   jobs.swap(jobs_);
   for (JobMap::iterator it = jobs.begin(); it != jobs.end(); ++it) {
     AbortJob(it->second);
     it->second->Cancel();
   }
 }
 
 }  // namespace net