Move v8_use_external_startup_data out of //build/config:feature_flags.

net/BUILD.gn

 # Copyright (c) 2013 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/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//build_overrides/v8.gni")
@@ skipping 719 matching lines @@
       "proxy/proxy_resolver_v8.h",
       "proxy/proxy_resolver_v8_tracing.cc",
       "proxy/proxy_resolver_v8_tracing.h",
       "proxy/proxy_resolver_v8_tracing_wrapper.cc",
       "proxy/proxy_resolver_v8_tracing_wrapper.h",
       "proxy/proxy_service_v8.cc",
       "proxy/proxy_service_v8.h",
     ]
 
     defines = [ "NET_IMPLEMENTATION" ]
+
     configs += [
       "//build/config/compiler:no_size_t_to_int_warning",
       "//build/config/compiler:wexit_time_destructors",
+      "//v8:external_startup_data",
     ]
 
     public_deps = [
       ":net",
     ]
     deps = [
       "//base",
       "//gin",
       "//url",
       "//v8",
@@ skipping 885 matching lines @@
   if (enable_websockets) {
     sources += [ "websockets/websocket_frame_perftest.cc" ]
   }
 
   if (use_v8_in_net) {
     deps += [ ":net_with_v8" ]
   } else {
     sources -= [ "proxy/proxy_resolver_perftest.cc" ]
   }
 }