Load CMA backend from shared library

chromecast/media/base/cast_media_default.cc

Index: chromecast/media/base/cast_media_default.cc
diff --git a/chromecast/media/base/cast_media_default.cc b/chromecast/media/base/cast_media_default.cc
index 0c177126ad6b3c9679001e20d3692bac941821b8..703cb4e9752770c58e6d6de950ff5e446c5d2a6d 100644
--- a/chromecast/media/base/cast_media_default.cc
+++ b/chromecast/media/base/cast_media_default.cc
@@ -2,8 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include "chromecast/media/cma/backend/media_pipeline_backend_default.h"
 #include "chromecast/public/cast_media_shlib.h"
 #include "chromecast/public/graphics_types.h"
+#include "chromecast/public/media_codec_support_shlib.h"
 #include "chromecast/public/video_plane.h"
 
 namespace chromecast {
@@ -42,5 +44,15 @@ VideoPlane* CastMediaShlib::GetVideoPlane() {
   return g_video_plane;
 }
 
+MediaPipelineBackend* CastMediaShlib::CreateMediaPipelineBackend(
+    const MediaPipelineDeviceParams& params) {
+  return new MediaPipelineBackendDefault(params);
+}
+
+MediaCodecSupportShlib::CodecSupport MediaCodecSupportShlib::IsSupported(
+    const std::string& codec) {
+  return kDefault;
+}
+
 }  // namespace media
 }  // namespace chromecast