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

chromecast/media/cma/backend/media_pipeline_backend_wrapper.cc

 // 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.
 
 #include "chromecast/media/cma/backend/media_pipeline_backend_wrapper.h"
 
 #include "base/logging.h"
 #include "chromecast/media/cma/backend/media_pipeline_backend_manager.h"
 
 namespace chromecast {
 namespace media {
 
 MediaPipelineBackendWrapper::MediaPipelineBackendWrapper(
-    scoped_ptr<MediaPipelineBackend> backend,
+    MediaPipelineBackend* backend,
     int stream_type,
-    float stream_type_volume,
-    MediaPipelineBackendManager* backend_manager)
-    : backend_(std::move(backend)),
+    float stream_type_volume)
+    : backend_(backend),
       stream_type_(stream_type),
       audio_decoder_wrapper_(nullptr),
       stream_type_volume_(stream_type_volume),
-      is_initialized_(false),
-      backend_manager_(backend_manager) {
+      is_initialized_(false) {
   DCHECK(backend_);
 }
 
 MediaPipelineBackendWrapper::~MediaPipelineBackendWrapper() {
-  backend_manager_->OnMediaPipelineBackendDestroyed(this);
+  MediaPipelineBackendManager::OnMediaPipelineBackendDestroyed(this);
 }
 
 MediaPipelineBackend::AudioDecoder*
 MediaPipelineBackendWrapper::CreateAudioDecoder() {
   DCHECK(!is_initialized_);
   if (audio_decoder_wrapper_)
     return nullptr;
 
   audio_decoder_wrapper_.reset(
       new AudioDecoderWrapper(backend_->CreateAudioDecoder()));
@@ skipping 45 matching lines @@
 
 void MediaPipelineBackendWrapper::SetStreamTypeVolume(
     float stream_type_volume) {
   stream_type_volume_ = stream_type_volume;
   if (is_initialized_ && audio_decoder_wrapper_)
     audio_decoder_wrapper_->SetStreamTypeVolume(stream_type_volume_);
 }
 
 }  // namespace media
 }  // namespace chromecast