Move enable_webrtc to a buildflag header.

content/public/common/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/buildflag_header.gni")
 import("//build/config/chromecast_build.gni")
 import("//build/config/features.gni")
+import("//media/media_options.gni")
 import("//mojo/public/tools/bindings/mojom.gni")
 import("//ppapi/features/features.gni")
 import("//third_party/webrtc/build/webrtc.gni")
 
 # See //content/BUILD.gn for how this works.
 group("common") {
   if (is_component_build) {
     public_deps = [
       "//content",
     ]
@@ skipping 43 matching lines @@
     "content_switches.h",
     "mojo_channel_switches.h",
   ]
   sources = [
     "//content/common/content_export.h",
     "content_switches.cc",
     "mojo_channel_switches.cc",
   ]
 
   public_configs = [ ":static_switches_defines" ]
+
+  # Deps required by the above headers.
+  deps = [
+    "//media:media_features",
+  ]
 }
 
 # This target allows you to use the content_features constants and statically
 # link to it, without depending on the rest of content. This is only for use
 # without content, or you will get multiply defined symbols.
 source_set("static_features") {
   public = [
     "content_features.h",
   ]
   sources = [
@@ skipping 226 matching lines @@
   sources = [
     "window_container_type.mojom",
   ]
 }
 
 mojom("service_names") {
   sources = [
     "service_names.mojom",
   ]
 }