[chromecast] Deletes dead code to track MediaPipelineBackend.

BUG=571155

Review-Url: https://codereview.chromium.org/2340423002
Cr-Commit-Position: refs/heads/master@{#418999}

chromecast/media/cma/pipeline/media_pipeline_client.h

@@ -30,11 +30,6 @@ struct MediaPipelineClient {
 
   // Callback used to report the buffering status.
   ::media::BufferingStateCB buffering_state_cb;
-
-  // Callback used to report the creation and destruction of
-  // MediaPipelineBackend
-  base::Closure pipeline_backend_created_cb;
-  base::Closure pipeline_backend_destroyed_cb;
 };
 
 }  // namespace media

chromecast/media/cma/pipeline/media_pipeline_impl.cc

@@ -103,21 +103,10 @@ MediaPipelineImpl::~MediaPipelineImpl() {
   CMALOG(kLogControl) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
 
-  weak_factory_.InvalidateWeakPtrs();
-
   if (backend_state_ != BACKEND_STATE_UNINITIALIZED &&
       backend_state_ != BACKEND_STATE_INITIALIZED)
     metrics::CastMetricsHelper::GetInstance()->RecordApplicationEvent(
         "Cast.Platform.Ended");
-
-  // Since av pipeline still need to access device components in their
-  // destructor, it's important to delete them first.
-  video_pipeline_.reset();
-  audio_pipeline_.reset();
-  audio_decoder_.reset();
-  media_pipeline_backend_.reset();
-  if (!client_.pipeline_backend_destroyed_cb.is_null())
-    client_.pipeline_backend_destroyed_cb.Run();
 }
 
 void MediaPipelineImpl::Initialize(
@@ -126,9 +115,7 @@ void MediaPipelineImpl::Initialize(
   CMALOG(kLogControl) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
   audio_decoder_.reset();
-  media_pipeline_backend_.reset(media_pipeline_backend.release());
-  if (!client_.pipeline_backend_created_cb.is_null())
-    client_.pipeline_backend_created_cb.Run();
+  media_pipeline_backend_ = std::move(media_pipeline_backend);
 
   if (load_type == kLoadTypeURL || load_type == kLoadTypeMediaSource) {
     base::TimeDelta low_threshold(kLowBufferThresholdURL);

chromecast/media/cma/pipeline/media_pipeline_impl.h

@@ -99,10 +99,12 @@ class MediaPipelineImpl {
   // Cached here because CMA pipeline backend does not support rate == 0,
   // which is emulated by pausing the backend.
   float playback_rate_;
+
+  // Since av pipeline still need to access device components in their
+  // destructor, it's important to delete them first.
   std::unique_ptr<MediaPipelineBackend> media_pipeline_backend_;
   std::unique_ptr<AudioDecoderSoftwareWrapper> audio_decoder_;
   MediaPipelineBackend::VideoDecoder* video_decoder_;
-
   std::unique_ptr<AudioPipelineImpl> audio_pipeline_;
   std::unique_ptr<VideoPipelineImpl> video_pipeline_;
   std::unique_ptr<FlushTask> pending_flush_task_;