headless: Remove usage of worker domain

headless/lib/browser/headless_devtools_client_impl.cc

Index: headless/lib/browser/headless_devtools_client_impl.cc
diff --git a/headless/lib/browser/headless_devtools_client_impl.cc b/headless/lib/browser/headless_devtools_client_impl.cc
index 083a5e7628ff64212db0c1ed84bff56c99858dde..833b9dc49afb1d85c386d64865b20448c98cfa57 100644
--- a/headless/lib/browser/headless_devtools_client_impl.cc
+++ b/headless/lib/browser/headless_devtools_client_impl.cc
@@ -62,7 +62,6 @@ HeadlessDevToolsClientImpl::HeadlessDevToolsClientImpl()
       service_worker_domain_(this),
       target_domain_(this),
       tracing_domain_(this),
-      worker_domain_(this),
       browser_main_thread_(content::BrowserThread::GetTaskRunnerForThread(
           content::BrowserThread::UI)),
       weak_ptr_factory_(this) {}
@@ -289,10 +288,6 @@ tracing::Domain* HeadlessDevToolsClientImpl::GetTracing() {
   return &tracing_domain_;
 }
 
-worker::Domain* HeadlessDevToolsClientImpl::GetWorker() {
-  return &worker_domain_;
-}
-
 template <typename CallbackType>
 void HeadlessDevToolsClientImpl::FinalizeAndSendMessage(
     base::DictionaryValue* message,