Make USE_EXTERNAL_POPUP_MENU local to content.

content/renderer/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/config/chromecast_build.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build/split_static_library.gni")
+import("//content/common/features.gni")
 import("//media/media_options.gni")
 import("//ppapi/features/features.gni")
 import("//printing/features/features.gni")
 import("//third_party/webrtc/webrtc.gni")
 import("//tools/ipc_fuzzer/ipc_fuzzer.gni")
 
 if (is_component_build) {
   link_target_type = "source_set"
 } else {
   link_target_type = "split_static_library"
@@ skipping 402 matching lines @@
     "//cc/paint",
     "//cc/surfaces",
     "//cc/surfaces:surface_id",
     "//cc/surfaces:surfaces",
     "//components/discardable_memory/client",
     "//components/payments/content:payment_app",
     "//components/url_formatter",
     "//content:resources",
     "//content/child",
     "//content/common",
+    "//content/common:features",
     "//content/gpu:gpu_sources",
     "//content/public/child:child_sources",
     "//content/public/common:common_sources",
     "//content/public/common:feature_h264_with_openh264_ffmpeg",
     "//content/public/common:features",
     "//crypto:platform",
     "//device/base/synchronization",
     "//device/battery:mojo_bindings",
     "//device/gamepad/public/interfaces",
     "//device/screen_orientation/public/interfaces",
@@ skipping 503 matching lines @@
     # For the defines in mojo_media_config.
     public_configs = [ "//media/mojo/services:mojo_media_config" ]
   }
 
   if (!is_component_build) {
     public_deps = [
       ":renderer",
     ]
   }
 }