[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 5e3374710a7687fd4e125d9d307600799f55a5ee..08f6894b5715383328fada3c4a27d1aef003effc 100644
--- a/chrome/browser/io_thread.cc
+++ b/chrome/browser/io_thread.cc
@@ -106,51 +106,12 @@ class SystemURLRequestContext : public URLRequestContextWithUserAgent {
   }
 };
 
-net::HostResolver* CreateGlobalHostResolver(net::NetLog* net_log) {
-  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
-
-  size_t parallelism = net::HostResolver::kDefaultParallelism;
-
-  // Use the concurrency override from the command-line, if any.
-  if (command_line.HasSwitch(switches::kHostResolverParallelism)) {
-    std::string s =
-        command_line.GetSwitchValueASCII(switches::kHostResolverParallelism);
-
-    // Parse the switch (it should be a positive integer formatted as decimal).
-    int n;
-    if (base::StringToInt(s, &n) && n > 0) {
-      parallelism = static_cast<size_t>(n);
-    } else {
-      LOG(ERROR) << "Invalid switch for host resolver parallelism: " << s;
-    }
-  }
-
-  size_t retry_attempts = net::HostResolver::kDefaultRetryAttempts;
-
-  // Use the retry attempts override from the command-line, if any.
-  if (command_line.HasSwitch(switches::kHostResolverRetryAttempts)) {
-    std::string s =
-        command_line.GetSwitchValueASCII(switches::kHostResolverRetryAttempts);
-    // Parse the switch (it should be a non-negative integer).
-    int n;
-    if (base::StringToInt(s, &n) && n >= 0) {
-      retry_attempts = static_cast<size_t>(n);
-    } else {
-      LOG(ERROR) << "Invalid switch for host resolver retry attempts: " << s;
-    }
-  }
-
-  net::HostResolver* global_host_resolver = NULL;
-  if (command_line.HasSwitch(switches::kEnableAsyncDns)) {
-    global_host_resolver =
-        net::CreateAsyncHostResolver(parallelism, retry_attempts, net_log);
-  }
-
-  if (!global_host_resolver) {
-    global_host_resolver =
-      net::CreateSystemHostResolver(parallelism, retry_attempts, net_log);
-  }
+scoped_ptr<net::HostResolver> CreateGlobalHostResolver(net::NetLog* net_log) {
+  // Configured by ChromeBrowserFieldTrials::AsyncDnsFieldTrial.
+  scoped_ptr<net::HostResolver> global_host_resolver(
+      net::HostResolver::CreateDefaultResolver(net_log));
 
+  const CommandLine& command_line = *CommandLine::ForCurrentProcess();
   // Determine if we should disable IPv6 support.
   if (!command_line.HasSwitch(switches::kEnableIPv6)) {
     if (command_line.HasSwitch(switches::kDisableIPv6)) {
@@ -164,13 +125,13 @@ 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
@@ -413,8 +374,7 @@ void IOThread::Init() {
     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();