Support desktop media pipeline on Android for GN build.

media/cdm/ppapi/BUILD.gn

 # 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/features.gni")
 import("//chrome/version.gni")  # TODO layering violation!
 import("//media/cdm/ppapi/cdm_adapter.gni")
-
-# Android doesn't use ffmpeg.
-use_ffmpeg = !is_android
+import("//media/media_options.gni")
 
 # The GYP version supports build flags "use_fake_video_decoder" and
 # "use_vpx". These should be added here if necessary but its not clear if
 # they are required any more.
 shared_library("clearkeycdm") {
   sources = [
     "cdm_file_io_test.cc",
     "cdm_file_io_test.h",
     "external_clear_key/cdm_video_decoder.cc",
     "external_clear_key/cdm_video_decoder.h",
     "external_clear_key/clear_key_cdm.cc",
     "external_clear_key/clear_key_cdm.h",
     "external_clear_key/clear_key_cdm_common.h",
   ]
 
   # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
   defines = [ "CDM_IMPLEMENTATION" ]
 
   deps = [
     "//base",
     "//build/config/sanitizers:deps",
     "//media",  # For media::AudioTimestampHelper
     "//media:shared_memory_support",  # For media::AudioBus.
     "//url",
   ]
 
-  if (use_ffmpeg) {
+  if (media_use_ffmpeg) {
     sources += [
       "external_clear_key/ffmpeg_cdm_audio_decoder.cc",
       "external_clear_key/ffmpeg_cdm_audio_decoder.h",
       "external_clear_key/ffmpeg_cdm_video_decoder.cc",
       "external_clear_key/ffmpeg_cdm_video_decoder.h",
     ]
     defines += [ "CLEAR_KEY_CDM_USE_FFMPEG_DECODER" ]
     deps += [ "//third_party/ffmpeg" ]
   }
 
@@ skipping 12 matching lines @@
 
 cdm_adapter("clearkeycdmadapter") {
   # Check whether the plugin's origin URL is valid.
   defines = [ "CHECK_DOCUMENT_URL" ]
   deps = [
     ":clearkeycdm",
     ":clearkeycdmadapter_resources",
     "//ppapi/cpp",
   ]
 }