Adds a command-line flag indicating an open and listening socket to

headless/lib/browser/headless_browser_main_parts.cc

Index: headless/lib/browser/headless_browser_main_parts.cc
diff --git a/headless/lib/browser/headless_browser_main_parts.cc b/headless/lib/browser/headless_browser_main_parts.cc
index 6423a44113cbf75438d41e2e44fea22eb09aee35..d69471e2972b31cfb9fe8ea480f2e75047370e7f 100644
--- a/headless/lib/browser/headless_browser_main_parts.cc
+++ b/headless/lib/browser/headless_browser_main_parts.cc
@@ -29,7 +29,7 @@ void HeadlessBrowserMainParts::PreMainMessageLoopRun() {
     net_log_.reset(new HeadlessNetLog(log_path));
   }
 
-  if (browser_->options()->devtools_endpoint.address().IsValid()) {
+  if (browser_->options()->DevtoolsServerEnabled()) {
     StartLocalDevToolsHttpHandler(browser_->options());
     devtools_http_handler_started_ = true;
   }