Remove the dependence on BrowserThread::FILE for

net/tools/net_watcher/net_watcher.cc

Index: net/tools/net_watcher/net_watcher.cc
diff --git a/net/tools/net_watcher/net_watcher.cc b/net/tools/net_watcher/net_watcher.cc
index 02cb3987ace676f939ab7c0bf7529e5a6c9510e7..53ca175c7ed866eda43c5dd291152849faa1583b 100644
--- a/net/tools/net_watcher/net_watcher.cc
+++ b/net/tools/net_watcher/net_watcher.cc
@@ -181,7 +181,7 @@ int main(int argc, char* argv[]) {
   // Use the network loop as the file loop also.
   std::unique_ptr<net::ProxyConfigService> proxy_config_service(
       net::ProxyService::CreateSystemProxyConfigService(
-          network_loop.task_runner(), network_loop.task_runner()));
+          network_loop.task_runner()));
 
   // Uses |network_change_notifier|.
   net::NetworkChangeNotifier::AddIPAddressObserver(&net_watcher);