Move enable_webrtc to a buildflag header.

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")
 import("//build/config/features.gni")
 import("//testing/libfuzzer/fuzzer_test.gni")
 
 declare_args() {
   # Allows distributions to link pulseaudio directly (DT_NEEDED) instead of
@@ skipping 26 matching lines @@
   # it only provides demuxing, and is only useful for AC3/EAC3 audio
   # pass-through to HDMI sink on Chromecast.
   enable_ac3_eac3_audio_demuxing = proprietary_codecs && is_chromecast
 
   enable_mse_mpeg2ts_stream_parser =
       (proprietary_codecs && is_chromecast) || use_libfuzzer || use_afl
 
   # Enable HEVC/H265 demuxing. Actual decoding must be provided by the
   # platform. Enable by default for Chromecast.
   enable_hevc_demuxing = proprietary_codecs && is_chromecast
+
+  enable_webrtc = !is_ios
 }
 
 # Use a second declare_args() to pick up possible overrides of |use_cras|.
 declare_args() {
   # Enables runtime selection of PulseAudio library.
   use_pulseaudio = false
 
   # Enables runtime selection of ALSA library for audio.
   use_alsa = false
 
@@ skipping 66 matching lines @@
     }
   }
 }
 
 declare_args() {
   # This switch defines whether the Media Remoting implementation will be built.
   # When enabled, media is allowed to be renderer and played back on remote
   # devices when the tab is being casted and other conditions are met.
   enable_media_remoting = !is_chromecast && !is_ios && !is_android
 }