Add BUILD.gn files for chromecast/media

media/media_options.gni

 # Copyright 2014 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.
 
 declare_args() {
   # Allows distributions to link pulseaudio directly (DT_NEEDED) instead of
   # using dlopen. This helps with automated detection of ABI mismatches and
   # prevents silent errors.
   link_pulseaudio = false
 
@@ skipping 27 matching lines @@
     use_alsa = true
     if (!use_cras) {
       use_pulseaudio = true
     }
   }
 
   # Enables the MPEG2-TS stream parser for use with Media Source. Disabled by
   # default since it's not available on the normal Web Platform and costs money.
   enable_mpeg2ts_stream_parser = false
 
-  # Enables browser side Content Decryption Modules. Required for embedders
-  # (e.g. Android and ChromeCast) that use a browser side CDM.
-  enable_browser_cdms = is_android
-
   # Experiment to enable mojo based media renderer: http://crbug.com/431776
   enable_media_mojo_renderer = false
 
   # TODO(GYP): This should be a platform define.
   is_openbsd = false
 }