[Chromecast] Upgrade to new CMA backend API

chromecast/public/cast_media_shlib.h

Index: chromecast/public/cast_media_shlib.h
diff --git a/chromecast/public/cast_media_shlib.h b/chromecast/public/cast_media_shlib.h
index d523db881621fc3e0fde3c1336f4346158b646e0..01264ded1b80af3b2a586e2bf2651a1d2ab7f42f 100644
--- a/chromecast/public/cast_media_shlib.h
+++ b/chromecast/public/cast_media_shlib.h
@@ -42,9 +42,8 @@ class CHROMECAST_EXPORT CastMediaShlib {
   // called at any time.  The VideoPlane object must be destroyed in Finalize.
   static VideoPlane* GetVideoPlane();
 
-  // Creates a factory object for a media pipeline backend.  Called in the
-  // browser process, any number of times (once per media pipeline).  Each call
-  // must instantiate a new factory object
+  // Creates a media pipeline backend.  Called in the browser process for each
+  // media pipeline and raw audio stream.

[slan, 2015/10/06 19:34:00]

Even though each MediaPipelineBackend must be able to return 3+1 A/V decoders,
this interface returns a single global instance, and ownership is retained. Can
we add these details to the comment?

[kmackay, 2015/10/06 21:44:55]

Updated the comments. This function is called once to create a new backend
instance for each new media playback stream.

[slan, 2015/10/06 22:15:05]

Thanks, much clearer.

   static MediaPipelineBackend* CreateMediaPipelineBackend(
       const MediaPipelineDeviceParams& params);
 };