Splits PipelineImpl into main and media thread components.

media/blink/webmediaplayer_impl.cc

Index: media/blink/webmediaplayer_impl.cc
diff --git a/media/blink/webmediaplayer_impl.cc b/media/blink/webmediaplayer_impl.cc
index 832433691bd68828415cd0e6ee98628d11754c88..c4cd1170246743802e0d9a7f1e7d9f78f65bc7e1 100644
--- a/media/blink/webmediaplayer_impl.cc
+++ b/media/blink/webmediaplayer_impl.cc
@@ -230,25 +230,15 @@ WebMediaPlayerImpl::WebMediaPlayerImpl(
 }
 
 WebMediaPlayerImpl::~WebMediaPlayerImpl() {
-  client_->setWebLayer(NULL);
-
   DCHECK(main_task_runner_->BelongsToCurrentThread());
 
+  client_->setWebLayer(NULL);
   if (delegate_) {
     delegate_->PlayerGone(delegate_id_);
     delegate_->RemoveObserver(delegate_id_);
   }
 
-  // Abort any pending IO so stopping the pipeline doesn't get blocked.
   suppress_destruction_errors_ = true;

[sandersd (OOO until July 31), 2016/06/03 23:11:45]

Probably group this with setWebLayer().

[alokp, 2016/06/03 23:57:49]

Done.

-  if (data_source_)

[sandersd (OOO until July 31), 2016/06/03 23:11:45]

I don't see any change in PipelineImpl related to these deletions, but I'm also
not sure how Pipeline gets blocked. What's the reasoning here?

[alokp, 2016/06/03 23:57:49]

I can move these changes to a separate patch if you like. None of this code is
required. Pipeline::Stop stops the Demuxer, which in turn stops the data source
in correct order.

I also discovered that both - Demuxer and DataSource - have duplicate functions
named Stop, Abort, and Shutdown that do the same thing. We might be able to
remove some duplication there.

Pipeline::Stop blocks until the renderer is destroyed and demuxer is stopped on
the media thread using a WaitableEvent. We might be able to get rid of this
WaitableEvent if we moved the ownership of Demuxer and DataSource to
RendererWrapper. That would allow us to just post a DeleteSoon task for
RendererWrapper on the media thread. See my comment in Pipeline::Stop.

-    data_source_->Abort();
-  if (chunk_demuxer_) {
-    chunk_demuxer_->Shutdown();
-    chunk_demuxer_ = nullptr;
-  }
-
-  renderer_factory_.reset();
 
   // Pipeline must be stopped before it is destroyed.
   pipeline_.Stop();