media: Support MojoMediaApplication in GPU process.

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.
 
 import("//build/config/chromecast_build.gni")
 
 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.
@@ skipping 46 matching lines @@
   enable_mpeg2ts_stream_parser = is_chromecast
 
   # Enable HEVC/H265 demuxing. Actual decoding must be provided by the
   # platform. Enable by default for Chromecast.
   enable_hevc_demuxing = is_chromecast
 
   # Experiment to enable mojo media application: http://crbug.com/431776
   # Valid options are:
   # - "none": Do not use mojo media application.
   # - "browser": Use mojo media application hosted in the browser process.
+  # - "gpu": Use mojo media application hosted in the gpu process.
   # - "utility": Use mojo media application hosted in the utility process.
   enable_mojo_media = "none"
 
   # TODO(GYP): This should be a platform define.
   is_openbsd = false
 }