Add a build flag to configure bundling of HSTS preload list

net/features.gni

 # Copyright 2016 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")
 
 declare_args() {
   # If true, prune things down as needed for proto-quic build.
   is_proto_quic = false
 
@@ skipping 12 matching lines @@
   use_kerberos = !is_ios && !is_chromecast
 
   # Do not disable brotli filter by default.
   disable_brotli_filter = false
 
   # Multicast DNS.
   enable_mdns = is_win || is_linux
 
   # Reporting not used on iOS.
   enable_reporting = !is_ios
+
+  # Whether transport security preload list should be included. This flag should

[lgarron, 2017/07/11 19:29:04]

Nit: "Whether the transport security preload list..."

I would prefer to be more direct rather than mentioning general "tradeoffs" and
a spec. Also, the preload list includes more than HSTS.

How about this?

----------------------------

Include the transport security preload list. This list includes mechanisms (e.g.
HSTS, HPKP) to enforce trusted connections to a significant set of hardcoded
domains. It should not be disabled unless building a subset of the codebase
where several hundred KB of binary size are a large burden, and the application
is willing to take responsibility to make sure that all important connections
use HTTPS.

[xunjieli, 2017/07/11 20:27:34]

Done.

+  # not be changed without examining the risks and tradeoffs.
+  # HTTP strict transport security (HSTS) is defined in
+  # http://tools.ietf.org/html/ietf-websec-strict-transport-sec.
+  # Changing this flag to false will disable bundling of
+  # net/http/transport_security_state_static.json, which enforces domains-
+  # configured HSTS settings.
+  include_transport_security_state_preload_list = true
 }