CmaMediaPipelineClient to watch media pipeline status

chromecast/media/cma/pipeline/media_pipeline_impl.cc

Index: chromecast/media/cma/pipeline/media_pipeline_impl.cc
diff --git a/chromecast/media/cma/pipeline/media_pipeline_impl.cc b/chromecast/media/cma/pipeline/media_pipeline_impl.cc
index c9d0e288c76479a9604ef9e5c689fe7a440fe2c3..2c644f1a03015e37ccc5c90a2308bb31439be4a8 100644
--- a/chromecast/media/cma/pipeline/media_pipeline_impl.cc
+++ b/chromecast/media/cma/pipeline/media_pipeline_impl.cc
@@ -66,6 +66,15 @@ MediaPipelineImpl::MediaPipelineImpl()
 MediaPipelineImpl::~MediaPipelineImpl() {
   CMALOG(kLogControl) << __FUNCTION__;
   DCHECK(thread_checker_.CalledOnValidThread());
+
+  weak_factory_.InvalidateWeakPtrs();
+
+  // 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();
+  media_pipeline_backend_.reset();
+  client_.device_components_destroy_cb.Run();

[halliwell, 2015/08/25 00:48:34]

I think you have to check is_null before calling?

[yucliu1, 2015/08/25 00:53:11]

The SetClient requires that all the callbacks can not be null. And there's no
other places reset the callbacks.

[halliwell, 2015/08/25 01:02:49]

You didn't add DCHECKs to SetClient for these new CBs.  And you will find a
variety of other users of media pipeline (e.g. unit tests) need updating to set
the new CBs in their clients.  Given that these other users don't actually need
the CB, you may want to consider allowing it to be null.

[yucliu1, 2015/08/25 04:27:58]

Done.

 }
 
 void MediaPipelineImpl::Initialize(
@@ -75,6 +84,7 @@ void MediaPipelineImpl::Initialize(
   DCHECK(thread_checker_.CalledOnValidThread());
   media_pipeline_backend_.reset(media_pipeline_backend.release());
   clock_device_ = media_pipeline_backend_->GetClock();
+  client_.device_components_create_cb.Run();

[halliwell, 2015/08/25 00:48:34]

same here.

[yucliu1, 2015/08/25 04:27:58]

Done.

 
   if (load_type == kLoadTypeURL || load_type == kLoadTypeMediaSource) {
     base::TimeDelta low_threshold(kLowBufferThresholdURL);