Pipeline: Use WeakPtr for DemuxerHost Calls and Tasks.

media/base/pipeline.h

Index: media/base/pipeline.h
diff --git a/media/base/pipeline.h b/media/base/pipeline.h
index 7c79b3f41762b0810d33ad3c9fa740b1e8b15a86..c4e858dfc8348d142bcd0336d030573a1d5ba1e0 100644
--- a/media/base/pipeline.h
+++ b/media/base/pipeline.h
@@ -430,6 +430,11 @@ class MEDIA_EXPORT Pipeline : public DemuxerHost {
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<Pipeline> weak_factory_;
 
+  // Demuxer calls can be made on the render main thread, where we cannot call
+  // weak_factory_.GetWeakPtr() to get weak pointers. Instead, use a permanent

[scherkus (not reviewing), 2014/08/05 18:11:30]

you sure about this?

I'm fairly certain GetWeakPtr() is OK to call on different threads, it's that
you cannot inspect/dereference the pointer on a different thread 

[xhwang, 2014/08/05 20:44:46]

Cool, I didn't know that. Double checked weak_ptr.h and you are right. This
actually makes the CL much simpler.

+  // weak pointer which will be initialized during the Demuxer initialization.
+  base::WeakPtr<Pipeline> weak_this_for_demuxer_;
+
   DISALLOW_COPY_AND_ASSIGN(Pipeline);
 };