Unconditionally build VP9 support.

webrtc/build/webrtc.gni

 # Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
 #
 # Use of this source code is governed by a BSD-style license
 # that can be found in the LICENSE file in the root of the source
 # tree. An additional intellectual property rights grant can be found
 # in the file PATENTS.  All contributing project authors may
 # be found in the AUTHORS file in the root of the source tree.
 
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
@@ skipping 25 matching lines @@
 
   # Disable these to not build components which can be externally provided.
   rtc_build_expat = true
   rtc_build_json = true
   rtc_build_libjpeg = true
   rtc_build_libvpx = true
   rtc_build_libyuv = true
   rtc_build_openmax_dl = true
   rtc_build_opus = true
   rtc_build_ssl = true
-  rtc_build_vp9 = true
 
   # Disable by default.
   rtc_have_dbus_glib = false
 
   # Enable to use the Mozilla internal settings.
   build_with_mozilla = false
 
   rtc_enable_android_opensl = false
 
   # Link-Time Optimizations.
@@ skipping 34 matching lines @@
   # Enable this to use HW H.264 encoder/decoder on iOS PeerConnections.
   # Enabling this may break interop with Android clients that support H264.
   rtc_use_objc_h264 = false
 }
 
 # Make it possible to provide custom locations for some libraries (move these
 # up into declare_args should we need to actually use them for the GN build).
 rtc_libvpx_dir = "//third_party/libvpx_new"
 rtc_libyuv_dir = "//third_party/libyuv"
 rtc_opus_dir = "//third_party/opus"