Remove unused WebThread based code for workers

content/child/worker_task_runner.h

Index: content/child/worker_task_runner.h
diff --git a/content/child/worker_task_runner.h b/content/child/worker_task_runner.h
index 3d720934e48edbfb646bac8c308662e1c8088ad3..6230551989b5d457677df988acb9d954c6fb8bf7 100644
--- a/content/child/worker_task_runner.h
+++ b/content/child/worker_task_runner.h
@@ -12,7 +12,6 @@
 #include "base/synchronization/lock.h"
 #include "base/threading/thread_local.h"
 #include "content/common/content_export.h"
-#include "third_party/WebKit/public/platform/WebThread.h"
 #include "third_party/WebKit/public/platform/WebWorkerRunLoop.h"
 
 namespace content {
@@ -40,14 +39,10 @@ class CONTENT_EXPORT WorkerTaskRunner {
   void OnWorkerRunLoopStarted(const blink::WebWorkerRunLoop& loop);
   void OnWorkerRunLoopStopped(const blink::WebWorkerRunLoop& loop);
 
-  void OnWorkerThreadStarted(blink::WebThread* thread);
-  void OnWorkerThreadStopped(blink::WebThread* thread);
-
  private:
   friend class WorkerTaskRunnerTest;
 
   typedef std::map<int, blink::WebWorkerRunLoop> IDToLoopMap;
-  typedef std::map<int, blink::WebThread*> IDToThreadMap;
 
   ~WorkerTaskRunner();
 
@@ -56,7 +51,6 @@ class CONTENT_EXPORT WorkerTaskRunner {
 
   base::AtomicSequenceNumber id_sequence_;
   IDToLoopMap loop_map_;
-  IDToThreadMap thread_map_;
   base::Lock loop_map_lock_;
 };