workers: Remove dead code.

content/child/worker_thread_task_runner.cc

Index: content/child/worker_thread_task_runner.cc
diff --git a/content/child/worker_thread_task_runner.cc b/content/child/worker_thread_task_runner.cc
index 8e5b2e75a4e4266e77be471b53bed5361fe17cf8..da7bc912fb9b780d2234b8d9500b07f93fbfca9e 100644
--- a/content/child/worker_thread_task_runner.cc
+++ b/content/child/worker_thread_task_runner.cc
@@ -13,13 +13,6 @@ WorkerThreadTaskRunner::WorkerThreadTaskRunner(int worker_thread_id)
     : worker_thread_id_(worker_thread_id) {
 }
 
-scoped_refptr<WorkerThreadTaskRunner> WorkerThreadTaskRunner::current() {
-  int worker_thread_id = WorkerTaskRunner::Instance()->CurrentWorkerId();
-  if (!worker_thread_id)
-    return scoped_refptr<WorkerThreadTaskRunner>();
-  return make_scoped_refptr(new WorkerThreadTaskRunner(worker_thread_id));
-}
-
 bool WorkerThreadTaskRunner::PostDelayedTask(
     const tracked_objects::Location& /* from_here */,
     const base::Closure& task,