Motown: ffmpeg implementations of framework 'parts'

services/media/framework_create/BUILD.gn

 # Copyright 2016 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.
 
 import("//build/module_args/mojo.gni")
 import("$mojo_sdk_root/mojo/public/mojo_sdk.gni")
 
 source_set("framework_create") {
   sources = [
     "decoder.cc",
     "demux.cc",
   ]
 
   deps = [
     "//services/media/framework",
+    "//services/media/framework_ffmpeg",
   ]
 }