media: Introduce DemuxerStreamProvider interface.

media/base/demuxer.h

Index: media/base/demuxer.h
diff --git a/media/base/demuxer.h b/media/base/demuxer.h
index c6b2515f178cbf883f7bde39df3dd2850145ca3e..7b0957be1dbe3cadcb9a264702ed295f60004c99 100644
--- a/media/base/demuxer.h
+++ b/media/base/demuxer.h
@@ -10,6 +10,7 @@
 #include "base/time/time.h"
 #include "media/base/data_source.h"
 #include "media/base/demuxer_stream.h"
+#include "media/base/demuxer_stream_provider.h"
 #include "media/base/media_export.h"
 #include "media/base/pipeline_status.h"
 
@@ -42,14 +43,8 @@ class MEDIA_EXPORT DemuxerHost {
   virtual ~DemuxerHost();
 };
 
-class MEDIA_EXPORT Demuxer {
+class MEDIA_EXPORT Demuxer : public DemuxerStreamProvider {

[scherkus (not reviewing), 2014/09/05 23:23:21]

alternatively we can go the composition route and have Demuxer() provide a
DemuxerStreamProvider* getter, similar to what I did with TimeSource* from
AudioRenderer

but I suppose we'd only really want to do that if it'd make sense for there to
be stand alone DSP implementations (similar to how I have WallClockTimeSource
vs. AudioRendererImpl).

[xhwang, 2014/09/09 21:25:01]

Yeah, currently both ChunkDemuxer and FFD provides the DS's directly. I don't
feel very necessary to add a DemuxerStreamProvider impl for them right now. So I
tend to land this right now and iterate on that later...

  public:
-  enum Liveness {
-    LIVENESS_UNKNOWN,
-    LIVENESS_RECORDED,
-    LIVENESS_LIVE,
-  };
-
   // A new potentially encrypted stream has been parsed.
   // First parameter - The type of initialization data.
   // Second parameter - The initialization data associated with the stream.
@@ -78,16 +73,13 @@ class MEDIA_EXPORT Demuxer {
   // call any method (including Stop()) after a demuxer has stopped.
   virtual void Stop(const base::Closure& callback) = 0;
 
-  // Returns the first stream of the given stream type (which is not allowed
-  // to be DemuxerStream::TEXT), or NULL if that type of stream is not present.
-  virtual DemuxerStream* GetStream(DemuxerStream::Type type) = 0;
-
   // Returns Time represented by presentation timestamp 0.
   // If the timstamps are not associated with a Time, then
   // a null Time is returned.
   virtual base::Time GetTimelineOffset() const = 0;
 
-  // Returns liveness of the stream, i.e. whether it is recorded or live.
+  // DemuxerStreamProvider implementation.

[scherkus (not reviewing), 2014/09/05 23:23:22]

I forget this part of C++ -- but do we need to duplicate these definitions here?

[xhwang, 2014/09/09 21:25:01]

No, it's not needed. Removed.

+  virtual DemuxerStream* GetStream(DemuxerStream::Type type) = 0;
   virtual Liveness GetLiveness() const = 0;
 
  private: