[Chromecast] Limit number of concurrent audio and video decoders

chromecast/media/cma/backend/media_pipeline_backend_wrapper.cc

Index: chromecast/media/cma/backend/media_pipeline_backend_wrapper.cc
diff --git a/chromecast/media/cma/backend/media_pipeline_backend_wrapper.cc b/chromecast/media/cma/backend/media_pipeline_backend_wrapper.cc
index 89cd79a41f5a704dc76d94461e8b44a76cbd6825..95675a4b87c2356fa8e2f25d69353c4c0ce14c77 100644
--- a/chromecast/media/cma/backend/media_pipeline_backend_wrapper.cc
+++ b/chromecast/media/cma/backend/media_pipeline_backend_wrapper.cc
@@ -34,6 +34,9 @@ MediaPipelineBackendWrapper::CreateAudioDecoder() {
   if (audio_decoder_wrapper_)
     return nullptr;
 
+  if (!backend_manager_->CanCreateAudioDecoder(this))
+    return nullptr;
+
   audio_decoder_wrapper_.reset(
       new AudioDecoderWrapper(backend_->CreateAudioDecoder()));
   return audio_decoder_wrapper_.get();
@@ -42,6 +45,9 @@ MediaPipelineBackendWrapper::CreateAudioDecoder() {
 MediaPipelineBackend::VideoDecoder*
 MediaPipelineBackendWrapper::CreateVideoDecoder() {
   DCHECK(!is_initialized_);
+  if (!backend_manager_->CanCreateVideoDecoder(this))
+    return nullptr;
+
   return backend_->CreateVideoDecoder();
 }