Cast: Don't create threads for each CastSessionDelegate

chrome/renderer/media/cast_threads.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.
+
+// Manages threads used by Cast Streaming Extensions API. There is a
+// singleton object of this class in the renderer.
+//
+// There are two threads owned by this class:
+// 1. Audio encode thread.
+// 2. Video encode thread.
+// These two threads are started this object is created.
+
+#ifndef CHROME_RENDERER_MEDIA_CAST_THREADS_H_
+#define CHROME_RENDERER_MEDIA_CAST_THREADS_H_
+
+#include "base/lazy_instance.h"
+#include "base/threading/thread.h"
+
+class CastThreads {
+ public:
+  scoped_refptr<base::SingleThreadTaskRunner>
+  GetAudioEncodeMessageLoopProxy();
+  scoped_refptr<base::SingleThreadTaskRunner>
+  GetVideoEncodeMessageLoopProxy();
+
+ private:
+  friend struct base::DefaultLazyInstanceTraits<CastThreads>;
+
+  CastThreads();
+
+  base::Thread audio_encode_thread_;
+  base::Thread video_encode_thread_;
+
+  DISALLOW_COPY_AND_ASSIGN(CastThreads);
+};
+
+#endif  // CHROME_RENDERER_MEDIA_CAST_THREADS_H_