web-threads: Create a single instance of WebThread for each blink thread.

content/child/webthread_impl.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_CHILD_WEBTHREAD_IMPL_H_
 #define CONTENT_CHILD_WEBTHREAD_IMPL_H_
 
 #include <map>
 
 #include "base/memory/scoped_ptr.h"
@@ skipping 62 matching lines @@
 
   // WebThreadBase implementation.
   base::SingleThreadTaskRunner* TaskRunner() const override;
 
  private:
   base::MessageLoop* MessageLoop() const override;
 
   scoped_ptr<base::Thread> thread_;
 };
 
-class WebThreadImplForMessageLoop : public WebThreadBase {
- public:
-  CONTENT_EXPORT explicit WebThreadImplForMessageLoop(
-      scoped_refptr<base::SingleThreadTaskRunner> owning_thread_task_runner);
-  CONTENT_EXPORT virtual ~WebThreadImplForMessageLoop();
-
-  // blink::WebThread implementation.
-  blink::PlatformThreadId threadId() const override;
-
-  // WebThreadBase implementation.
-  base::MessageLoop* MessageLoop() const override;
-
- private:
-  base::SingleThreadTaskRunner* TaskRunner() const override;
-
-  scoped_refptr<base::SingleThreadTaskRunner> owning_thread_task_runner_;
-  blink::PlatformThreadId thread_id_;
-};
-
 } // namespace content
 
 #endif  // CONTENT_CHILD_WEBTHREAD_IMPL_H_