[Chromecast] Limit number of concurrent audio and video decoders

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 49227383e414f2b37af46db4d778c4db3cec5e49..6fa18df86cada8d5d9eceeeac3b16b729be7e840 100644
--- a/chromecast/media/cma/backend/media_pipeline_backend_manager.cc
+++ b/chromecast/media/cma/backend/media_pipeline_backend_manager.cc
@@ -15,8 +15,9 @@ namespace media {
 
 MediaPipelineBackendManager::MediaPipelineBackendManager(
     scoped_refptr<base::SingleThreadTaskRunner> media_task_runner)
-    : media_task_runner_(std::move(media_task_runner)) {
-}
+    : media_task_runner_(std::move(media_task_runner)),
+      audio_decoder_count_(0),
+      video_decoder_count_(0) {}
 
 MediaPipelineBackendManager::~MediaPipelineBackendManager() {
 }
@@ -42,6 +43,38 @@ MediaPipelineBackendManager::CreateMediaPipelineBackend(
   return backend_ptr;
 }
 
+bool MediaPipelineBackendManager::IncrementAudioDecoderCount() {

[alokp, 2016/07/22 16:46:44]

nit: You may want to merge the implementation for audio/video by passing decoder
type into Increment/DecrementDecoderCount(DecoderType).

[halliwell, 2016/07/22 17:16:29]

Done.

+  DCHECK(media_task_runner_->BelongsToCurrentThread());
+  if (audio_decoder_count_ >= 2) {
+    LOG(WARNING) << "AudioDecoder limit reached";
+    return false;
+  }
+
+  ++audio_decoder_count_;
+  return true;
+}
+
+bool MediaPipelineBackendManager::IncrementVideoDecoderCount() {
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
+  if (video_decoder_count_ >= 1) {
+    LOG(WARNING) << "VideoDecoder limit reached";
+    return false;
+  }
+
+  ++video_decoder_count_;
+  return true;
+}
+
+void MediaPipelineBackendManager::DecrementAudioDecoderCount() {
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
+  audio_decoder_count_--;

[alokp, 2016/07/22 16:46:44]

DCHECK(audio_decoder_count_ > 0)

[halliwell, 2016/07/22 17:16:29]

Done.

+}
+
+void MediaPipelineBackendManager::DecrementVideoDecoderCount() {
+  DCHECK(media_task_runner_->BelongsToCurrentThread());
+  video_decoder_count_--;

[alokp, 2016/07/22 16:46:44]

ditto

[halliwell, 2016/07/22 17:16:29]

Done.

+}
+
 void MediaPipelineBackendManager::OnMediaPipelineBackendDestroyed(
     const MediaPipelineBackend* backend) {
   DCHECK(media_task_runner_->BelongsToCurrentThread());