Move ProxyConfigService construction onto the IO thread.

net/url_request/url_request_context_builder.cc

Index: net/url_request/url_request_context_builder.cc
diff --git a/net/url_request/url_request_context_builder.cc b/net/url_request/url_request_context_builder.cc
index 3228bfbdf61ec66ec61c4a5b324aabadd7232a94..83e443fbc846992be65f9f8c25d97163b1845ab4 100644
--- a/net/url_request/url_request_context_builder.cc
+++ b/net/url_request/url_request_context_builder.cc
@@ -145,7 +145,7 @@ class BasicURLRequestContext : public URLRequestContext {
 
   void StartFileThread() {
     file_thread_.StartWithOptions(
-        base::Thread::Options(MessageLoop::TYPE_DEFAULT, 0));
+        base::Thread::Options(MessageLoop::TYPE_IO, 0));
   }
 
   MessageLoop* file_message_loop() {
@@ -194,13 +194,17 @@ URLRequestContextBuilder::HttpNetworkSessionParams::~HttpNetworkSessionParams()
 
 URLRequestContextBuilder::URLRequestContextBuilder()
     : ftp_enabled_(false),
+#if defined(OS_LINUX)
+      glib_task_runner_(NULL),
+#endif  // defined(OS_LINUX)
       http_cache_enabled_(true) {}
+
 URLRequestContextBuilder::~URLRequestContextBuilder() {}
 
 #if defined(OS_LINUX)
-void URLRequestContextBuilder::set_proxy_config_service(
-    ProxyConfigService* proxy_config_service) {
-  proxy_config_service_.reset(proxy_config_service);
+void URLRequestContextBuilder::set_glib_task_runner(
+    base::SingleThreadTaskRunner* glib_task_runner) {
+  glib_task_runner_ = glib_task_runner;
 }
 #endif  // defined(OS_LINUX)
 
@@ -225,19 +229,15 @@ URLRequestContext* URLRequestContextBuilder::Build() {
 
   context->StartFileThread();
 
-  // TODO(willchan): Switch to using this code when
-  // ProxyService::CreateSystemProxyConfigService()'s signature doesn't suck.
+  storage->set_proxy_service(
+      ProxyService::CreateUsingSystemProxyResolver(
+          ProxyService::CreateSystemProxyConfigService(
 #if defined(OS_LINUX)
-  ProxyConfigService* proxy_config_service = proxy_config_service_.release();
+              glib_task_runner_,
 #else
-  ProxyConfigService* proxy_config_service =
-      ProxyService::CreateSystemProxyConfigService(
-          base::ThreadTaskRunnerHandle::Get(),
-          context->file_message_loop());
+              NULL,
 #endif  // defined(OS_LINUX)
-  storage->set_proxy_service(
-      ProxyService::CreateUsingSystemProxyResolver(
-          proxy_config_service,
+              context->file_message_loop()),
           4,  // TODO(willchan): Find a better constant somewhere.
           context->net_log()));
   storage->set_ssl_config_service(new net::SSLConfigServiceDefaults);