Load CMA backend from shared library

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 8b776da8a43504a11ddaf9eb2ee24d361c4419a9..d523db881621fc3e0fde3c1336f4346158b646e0 100644
--- a/chromecast/public/cast_media_shlib.h
+++ b/chromecast/public/cast_media_shlib.h
@@ -13,6 +13,8 @@
 namespace chromecast {
 namespace media {
 
+class MediaPipelineBackend;
+struct MediaPipelineDeviceParams;
 class VideoPlane;
 
 // Provides access to platform-specific media systems and hardware resources.
@@ -39,6 +41,12 @@ class CHROMECAST_EXPORT CastMediaShlib {
   // While an implementation is in an initialized state, this function may be
   // 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
+  static MediaPipelineBackend* CreateMediaPipelineBackend(
+      const MediaPipelineDeviceParams& params);
 };
 
 }  // namespace media