[net] Change factory methods for HostResolver and HostCache to return a scoped_ptr

chrome/browser/io_thread.cc

Index: chrome/browser/io_thread.cc
diff --git a/chrome/browser/io_thread.cc b/chrome/browser/io_thread.cc
index 491f4febe020bb68f43c61c30b7a4ae595ede63f..a9cb57c257357aeffab70e0d9732b56ee849b735 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -108,7 +108,7 @@ class SystemURLRequestContext : public URLRequestContextWithUserAgent {
   }
 };
 
-net::HostResolver* CreateGlobalHostResolver(net::NetLog* net_log) {
+scoped_ptr<net::HostResolver> CreateGlobalHostResolver(net::NetLog* net_log) {
   const CommandLine& command_line = *CommandLine::ForCurrentProcess();
 
   bool allow_async_dns_field_trial = true;
@@ -146,7 +146,6 @@ net::HostResolver* CreateGlobalHostResolver(net::NetLog* net_log) {
     }
   }
 
-  net::HostResolver* global_host_resolver = NULL;
   bool use_async = false;
   if (command_line.HasSwitch(switches::kEnableAsyncDns)) {
     allow_async_dns_field_trial = false;
@@ -159,13 +158,12 @@ net::HostResolver* CreateGlobalHostResolver(net::NetLog* net_log) {
   if (allow_async_dns_field_trial)
     use_async = chrome_browser_net::ConfigureAsyncDnsFieldTrial();
 
-  if (use_async) {
-    global_host_resolver =
-        net::CreateAsyncHostResolver(parallelism, retry_attempts, net_log);
-  } else {
-    global_host_resolver =
-        net::CreateSystemHostResolver(parallelism, retry_attempts, net_log);
-  }
+  scoped_ptr<net::HostResolver> global_host_resolver(
+      net::HostResolver::CreateSystemResolver(parallelism,
+                                              retry_attempts,
+                                              true /* use_cache */,

[darin (slow to review), 2012/10/09 17:38:34]

I'm not a big fan of functions that take multiples bool parameters.  It is
really easy to make a mistake at the callsite.  You might consider defining an
Options struct with bool member variables that can be set.  See for example
Thread::StartWithOptions.  You could also use bit masks that you OR together.

[szym, 2012/10/09 21:40:43]

Done.

+                                              use_async,
+                                              net_log));
 
   // Determine if we should disable IPv6 support.
   if (!command_line.HasSwitch(switches::kEnableIPv6)) {
@@ -180,13 +178,13 @@ net::HostResolver* CreateGlobalHostResolver(net::NetLog* net_log) {
   // rules on top of the real host resolver. This allows forwarding all requests
   // through a designated test server.
   if (!command_line.HasSwitch(switches::kHostResolverRules))
-    return global_host_resolver;
+    return global_host_resolver.PassAs<net::HostResolver>();
 
-  net::MappedHostResolver* remapped_resolver =
-      new net::MappedHostResolver(global_host_resolver);
+  scoped_ptr<net::MappedHostResolver> remapped_resolver(
+      new net::MappedHostResolver(global_host_resolver.Pass()));
   remapped_resolver->SetRulesFromString(
       command_line.GetSwitchValueASCII(switches::kHostResolverRules));
-  return remapped_resolver;
+  return remapped_resolver.PassAs<net::HostResolver>();
 }
 
 // TODO(willchan): Remove proxy script fetcher context since it's not necessary
@@ -438,8 +436,7 @@ void IOThread::Init() {
   if (command_line.HasSwitch(switches::kDisableExtensionsHttpThrottling))
     network_delegate->NeverThrottleRequests();
   globals_->system_network_delegate.reset(network_delegate);
-  globals_->host_resolver.reset(
-      CreateGlobalHostResolver(net_log_));
+  globals_->host_resolver = CreateGlobalHostResolver(net_log_);
   globals_->cert_verifier.reset(net::CertVerifier::CreateDefault());
   globals_->transport_security_state.reset(new net::TransportSecurityState());
   globals_->ssl_config_service = GetSSLConfigService();