Replace WIDEVINE_CDM_AVAILABLE with a gyp define 'enable_widevine_cdm'.

build/config/features.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.
 
 # This file contains UI-related build flags. It should theoretically be in the
 # src/ui directory and only things that depend on the ui module should get the
 # definitions.
 #
 # However, today we have many "bad" dependencies on some of these flags from,
 # e.g. base, so they need to be global.
@@ skipping 21 matching lines @@
   # --debug-devtools cmdline switch.
   debug_devtools = false
 
   # Enables WebRTC.
   #enable_webrtc = !is_ios  TODO(GYP) use this condition when WebRTC works in
   #                         the GN build.
   enable_webrtc = false
 
   # Enables proprietary codecs and demuxers; e.g. H264, MOV, AAC, and MP3.
   proprietary_codecs = false
+
+  # The Widevine CDM is enabled by default for Chrome builds, and is a platform
+  # feature on Android.
+  enable_widevine_cdm = is_chrome_branded || is_android
+
+  # Widevine is distributed as a component for Mac and Windows.
+  widevine_cdm_is_component = is_chrome_branded && (is_mac || is_win)
 }
 
 # Additional dependent variables -----------------------------------------------
 
 # Set the version of CLD.
 #   0: Don't specify the version. This option is for the Finch testing.
 #   1: Use only CLD1.
 #   2: Use only CLD2.
 if (is_android) {
   cld_version = 1
@@ skipping 105 matching lines @@
 
 # Option controlling the use of GConf (the classic GNOME configuration
 # system).
 # TODO(GYP) also require !embedded to enable.
 use_gconf = is_linux && !is_chromeos
 
 # Hangout services is an extension that adds extra features to Hangouts.
 # For official GYP builds, this flag is set, it will likely need to be
 # parameterized in the future for a similar use.
 enable_hangout_services_extension = false