[Chromecast] Fix ordering in PreMainMessageLoopRun

chromecast/browser/url_request_context_factory.cc

Index: chromecast/browser/url_request_context_factory.cc
diff --git a/chromecast/browser/url_request_context_factory.cc b/chromecast/browser/url_request_context_factory.cc
index 5b938fb4bee6b25fdb6a84b8f864d33fa2710da0..af3ba856a9be21d532f54babf429650e3141d3fa 100644
--- a/chromecast/browser/url_request_context_factory.cc
+++ b/chromecast/browser/url_request_context_factory.cc
@@ -247,6 +247,7 @@ void URLRequestContextFactory::InitializeSystemContextDependencies() {
   // in the future.
   http_server_properties_.reset(new net::HttpServerPropertiesImpl);
 
+  DCHECK(proxy_config_service_);
   proxy_service_ = net::ProxyService::CreateUsingSystemProxyResolver(
       std::move(proxy_config_service_), 0, NULL);
   system_dependencies_initialized_ = true;