[chromecast] Pass media task runner to MediaPipelineBackendManager.

chromecast/media/cma/backend/media_pipeline_backend_manager.cc

Index: chromecast/media/cma/backend/media_pipeline_backend_manager.cc
diff --git a/chromecast/media/cma/backend/media_pipeline_backend_manager.cc b/chromecast/media/cma/backend/media_pipeline_backend_manager.cc
index d0db5adf3e4ed750f0e08710e307add1f519f44c..650a027aae20f8ac90c57fb1ae2af6184cea46cd 100644
--- a/chromecast/media/cma/backend/media_pipeline_backend_manager.cc
+++ b/chromecast/media/cma/backend/media_pipeline_backend_manager.cc
@@ -6,65 +6,59 @@
 
 #include <algorithm>
 
-#include "base/bind.h"
-#include "base/lazy_instance.h"
-#include "base/location.h"
-#include "chromecast/media/base/media_message_loop.h"
+#include "base/single_thread_task_runner.h"
 #include "chromecast/media/cma/backend/media_pipeline_backend_wrapper.h"
 #include "chromecast/public/cast_media_shlib.h"
 
 namespace chromecast {
 namespace media {
 
-namespace {
-
-base::LazyInstance<MediaPipelineBackendManager> g_instance =
-    LAZY_INSTANCE_INITIALIZER;
+MediaPipelineBackendManager::MediaPipelineBackendManager(
+    scoped_refptr<base::SingleThreadTaskRunner> media_task_runner)
+    : media_task_runner_(std::move(media_task_runner)) {
+}
 
-}  // namespace
+MediaPipelineBackendManager::~MediaPipelineBackendManager() {
+}
 
-// static
-MediaPipelineBackend* MediaPipelineBackendManager::CreateMediaPipelineBackend(
+scoped_ptr<MediaPipelineBackend>
+MediaPipelineBackendManager::CreateMediaPipelineBackend(
     const media::MediaPipelineDeviceParams& params) {
-  DCHECK(MediaMessageLoop::GetTaskRunner()->BelongsToCurrentThread());
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
   return CreateMediaPipelineBackend(params, 0);
 }
 
-// static
-MediaPipelineBackend* MediaPipelineBackendManager::CreateMediaPipelineBackend(
+scoped_ptr<MediaPipelineBackend>
+MediaPipelineBackendManager::CreateMediaPipelineBackend(
     const media::MediaPipelineDeviceParams& params,
     int stream_type) {
-  DCHECK(MediaMessageLoop::GetTaskRunner()->BelongsToCurrentThread());
-  MediaPipelineBackendManager* backend_manager = Get();
-  MediaPipelineBackendWrapper* backend_ptr = new MediaPipelineBackendWrapper(
-      media::CastMediaShlib::CreateMediaPipelineBackend(params), stream_type,
-      backend_manager->GetVolumeMultiplier(stream_type));
-  backend_manager->media_pipeline_backends_.push_back(backend_ptr);
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
+  scoped_ptr<MediaPipelineBackend> backend_ptr(new MediaPipelineBackendWrapper(
+      make_scoped_ptr(
+          media::CastMediaShlib::CreateMediaPipelineBackend(params)),
+      stream_type, GetVolumeMultiplier(stream_type), this));
+  media_pipeline_backends_.push_back(backend_ptr.get());
   return backend_ptr;
 }
 
-// static
 void MediaPipelineBackendManager::OnMediaPipelineBackendDestroyed(
     const MediaPipelineBackend* backend) {
-  DCHECK(MediaMessageLoop::GetTaskRunner()->BelongsToCurrentThread());
-  MediaPipelineBackendManager* backend_manager = Get();
-  backend_manager->media_pipeline_backends_.erase(
-      std::remove(backend_manager->media_pipeline_backends_.begin(),
-                  backend_manager->media_pipeline_backends_.end(), backend),
-      backend_manager->media_pipeline_backends_.end());
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
+  media_pipeline_backends_.erase(
+      std::remove(media_pipeline_backends_.begin(),
+                  media_pipeline_backends_.end(), backend),
+      media_pipeline_backends_.end());
 }
 
-// static
 void MediaPipelineBackendManager::SetVolumeMultiplier(int stream_type,
                                                       float volume) {
-  DCHECK(MediaMessageLoop::GetTaskRunner()->BelongsToCurrentThread());
-  MediaPipelineBackendManager* backend_manager = Get();
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
   volume = std::max(0.0f, std::min(volume, 1.0f));
-  backend_manager->volume_by_stream_type_[stream_type] = volume;
+  volume_by_stream_type_[stream_type] = volume;
 
   // Set volume for each open media pipeline backends.
-  for (auto it = backend_manager->media_pipeline_backends_.begin();
-       it != backend_manager->media_pipeline_backends_.end(); it++) {
+  for (auto it = media_pipeline_backends_.begin();
+       it != media_pipeline_backends_.end(); it++) {
     MediaPipelineBackendWrapper* wrapper =
         static_cast<MediaPipelineBackendWrapper*>(*it);
     if (wrapper->GetStreamType() == stream_type)
@@ -72,22 +66,10 @@ void MediaPipelineBackendManager::SetVolumeMultiplier(int stream_type,
   }
 }
 
-// static
-MediaPipelineBackendManager* MediaPipelineBackendManager::Get() {
-  return g_instance.Pointer();
-}
-
-MediaPipelineBackendManager::MediaPipelineBackendManager() {
-}
-
-MediaPipelineBackendManager::~MediaPipelineBackendManager() {
-}
-
 float MediaPipelineBackendManager::GetVolumeMultiplier(int stream_type) {
-  DCHECK(MediaMessageLoop::GetTaskRunner()->BelongsToCurrentThread());
-  MediaPipelineBackendManager* backend_manager = Get();
-  auto it = backend_manager->volume_by_stream_type_.find(stream_type);
-  if (it == backend_manager->volume_by_stream_type_.end()) {
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
+  auto it = volume_by_stream_type_.find(stream_type);
+  if (it == volume_by_stream_type_.end()) {
     return 1.0;
   } else {
     return it->second;