Load CMA backend from shared library

chromecast/media/cma/base/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 source_set("base") {
   sources = [
     "balanced_media_task_runner_factory.cc",
     "balanced_media_task_runner_factory.h",
     "buffering_controller.cc",
     "buffering_controller.h",
     "buffering_defs.cc",
     "buffering_defs.h",
     "buffering_frame_provider.cc",
     "buffering_frame_provider.h",
     "buffering_state.cc",
     "buffering_state.h",
+    "cast_decoder_buffer_impl.cc",
+    "cast_decoder_buffer_impl.h",
+    "cast_decrypt_config_impl.cc",
+    "cast_decrypt_config_impl.h",
     "cma_logging.h",
     "coded_frame_provider.cc",
     "coded_frame_provider.h",
     "decoder_buffer_adapter.cc",
     "decoder_buffer_adapter.h",
-    "decoder_buffer_base.cc",
     "decoder_buffer_base.h",
     "decoder_config_adapter.cc",
     "decoder_config_adapter.h",
     "media_task_runner.cc",
     "media_task_runner.h",
     "simple_media_task_runner.cc",
     "simple_media_task_runner.h",
   ]
 
   configs += [ "//chromecast:config" ]
 
   deps = [
     "//base",
     "//chromecast/base",
     "//chromecast/base/metrics",
     "//media",
     "//media:shared_memory_support",
   ]
 }