Remove gcdPrivate API code.

chrome/common/extensions/api/BUILD.gn

 # Copyright 2015 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("//build/config/ui.gni")
 import("//chrome/common/features.gni")
 import("//extensions/features/features.gni")
 import("//media/media_options.gni")
 import("//tools/json_schema_compiler/json_features.gni")
@@ skipping 102 matching lines @@
     "quick_unlock_private.idl",
     "terminal_private.json",
     "users_private.idl",
     "wallpaper.json",
     "wallpaper_private.json",
   ]
 } else if (is_linux || is_win) {
   schema_sources += [ "input_ime.json" ]
 }
 if (enable_service_discovery) {
-  schema_sources += [
-    "gcd_private.idl",
-    "mdns.idl",
-  ]
+  schema_sources += [ "mdns.idl" ]
 }
 if (enable_webrtc) {
   schema_sources += [
     "cast_streaming_receiver_session.idl",
     "cast_streaming_rtp_stream.idl",
     "cast_streaming_session.idl",
     "cast_streaming_udp_transport.idl",
   ]
 }
 if (enable_app_list) {
@@ skipping 129 matching lines @@
 }
 
 group("extensions_features") {
   public_deps = [
     ":api_features",
     ":behavior_features",
     ":manifest_features",
     ":permission_features",
   ]
 }