Don't check is_ios in chrome/, it's always false there.

chrome/common/net/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/crypto.gni")
 
+assert(!is_ios, "Chromium/iOS shouldn't use anything in //chrome")
+
 static_library("net") {
   sources = [
     "net_resource_provider.cc",
     "net_resource_provider.h",
     "x509_certificate_model.cc",
     "x509_certificate_model.h",
     "x509_certificate_model_nss.cc",
   ]
 
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
   deps = [
     "//base",
     "//base:i18n",
     "//chrome:resources",
     "//chrome:strings",
     "//components/url_formatter",
     "//crypto",
     "//net",
     "//net:net_resources",
     "//third_party/icu",
     "//ui/base",
   ]
 
-  if (is_ios) {
-    sources -= [ "net_resource_provider.cc" ]
-  }
-
-  if (is_android || is_ios) {
+  if (is_android) {
     sources -= [ "x509_certificate_model.cc" ]
   }
 
   if (use_nss_certs) {
     deps += [
       "//chrome/third_party/mozilla_security_manager",
       "//crypto:platform",
     ]
     allow_circular_includes_from =
         [ "//chrome/third_party/mozilla_security_manager" ]
   } else {
     sources -= [ "x509_certificate_model_nss.cc" ]
   }
 }