Convert RLZ to a buildflag header

ios/chrome/browser/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/buildflag_header.gni")
 import("//build/config/features.gni")
 import("//build/config/ios/rules.gni")
+import("//rlz/features/features.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 declare_args() {
   google_test_gaia_client_id = ""
   google_test_gaia_client_secret = ""
   google_staging_api_url = ""
   google_staging_lso_url = ""
   google_test_api_url = ""
   google_test_lso_url = ""
   google_test_oauth_client_id = ""
@@ skipping 96 matching lines @@
     "//ios/chrome/app/strings",
     "//ios/chrome/browser/browser_state",
     "//ios/chrome/browser/sync/glue",
     "//ios/chrome/common",
     "//ios/net",
     "//ios/public/provider/chrome/browser",
     "//ios/public/provider/chrome/browser/voice",
     "//ios/web",
     "//ios/web:user_agent",
     "//net",
+    "//rlz/features",
     "//url",
   ]
   allow_circular_includes_from = [
     "//ios/chrome/browser/sync/glue",
     "//ios/chrome/browser/browser_state",
   ]
   libs = [ "UIKit.framework" ]
 }
 
 source_set("browser_impl") {
@@ skipping 41 matching lines @@
     "//ios/chrome/browser/prefs",
     "//ios/chrome/browser/services/gcm",
     "//ios/chrome/browser/translate",
     "//ios/chrome/browser/update_client",
     "//ios/chrome/browser/web_resource",
     "//ios/chrome/common",
     "//ios/public/provider/chrome/browser",
     "//ios/web",
     "//ios/web/public/app",
     "//net",
+    "//rlz/features",
     "//ui/base",
   ]
 
   if (enable_rlz) {
     deps += [ "//ios/chrome/browser/rlz" ]
   }
 }
 
 buildflag_header("google_api_keys_header") {
   header = "google_api_keys.h"
@@ skipping 38 matching lines @@
     "//components/proxy_config",
     "//components/ssl_config",
     "//components/variations",
     "//ios/web:test_support",
     "//net",
     "//net:test_support",
     "//testing/gtest",
     "//url",
   ]
 }