Revert of [chromecast] Pass media task runner to MediaPipelineBackendManager.

chromecast/media/cma/backend/media_pipeline_backend_wrapper.h

 // Copyright 2016 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 CHROMECAST_MEDIA_CMA_BACKEND_MEDIA_PIPELINE_BACKEND_WRAPPER_H_
 #define CHROMECAST_MEDIA_CMA_BACKEND_MEDIA_PIPELINE_BACKEND_WRAPPER_H_
 
 #include <stdint.h>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/time/time.h"
 #include "chromecast/media/cma/backend/audio_decoder_wrapper.h"
 #include "chromecast/public/media/media_pipeline_backend.h"
 #include "chromecast/public/media/media_pipeline_device_params.h"
 
 namespace base {
 class SingleThreadTaskRunner;
 }  // namespace base
 
 namespace chromecast {
 namespace media {
 
-class MediaPipelineBackendManager;
-
 class MediaPipelineBackendWrapper : public MediaPipelineBackend {
  public:
-  MediaPipelineBackendWrapper(scoped_ptr<MediaPipelineBackend> backend,
+  MediaPipelineBackendWrapper(MediaPipelineBackend* backend,
                               int stream_type,
-                              float stream_type_volume,
-                              MediaPipelineBackendManager* backend_manager);
+                              float stream_type_volume);
   ~MediaPipelineBackendWrapper() override;
 
   // MediaPipelineBackend implementation:
   AudioDecoder* CreateAudioDecoder() override;
   VideoDecoder* CreateVideoDecoder() override;
   bool Initialize() override;
   bool Start(int64_t start_pts) override;
   bool Stop() override;
   bool Pause() override;
   bool Resume() override;
   int64_t GetCurrentPts() override;
   bool SetPlaybackRate(float rate) override;
 
   int GetStreamType() const;
   void SetStreamTypeVolume(float stream_type_volume);
 
  private:
   scoped_ptr<MediaPipelineBackend> backend_;
   const int stream_type_;
   scoped_ptr<AudioDecoderWrapper> audio_decoder_wrapper_;
   float stream_type_volume_;
   bool is_initialized_;
-  MediaPipelineBackendManager* const backend_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaPipelineBackendWrapper);
 };
 
 }  // namespace media
 }  // namespace chromecast
 
 #endif  // CHROMECAST_MEDIA_CMA_BACKEND_MEDIA_PIPELINE_BACKEND_WRAPPER_H_