[ios] Create a new EG test suite for test depending on network.

ios/chrome/browser/translate/BUILD.gn

 # 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.
 
 source_set("translate") {
   sources = [
     "after_translate_infobar_controller.h",
     "after_translate_infobar_controller.mm",
     "before_translate_infobar_controller.h",
     "before_translate_infobar_controller.mm",
@@ skipping 55 matching lines @@
     "//ios/chrome/browser/web:test_support",
     "//ios/chrome/common",
     "//ios/public/provider/chrome/browser:test_support",
     "//ios/web",
     "//ios/web:test_support",
     "//testing/gtest",
     "//url",
   ]
 }
 
-source_set("eg_tests") {
+# Those tests do not use external URLs but fail if the network is unavailable
+# as they explicitly check whether the network is up or not; it is not possible
+# to safely instantiate a net::NetworkChangeNotifier::DisableForTest to disable
+# those checks as this in not thread-safe. See http://crbug.com/709131 for more
+# details.
+source_set("external_url_eg_tests") {
   testonly = true
   sources = [
     "translate_egtest.mm",
   ]
   deps = [
     ":translate",
     "//base",
     "//components/strings",
     "//components/translate/core/browser",
     "//components/translate/core/common",
     "//components/translate/ios/browser",
     "//ios/chrome/browser/browser_state",
     "//ios/chrome/test/app:test_support",
     "//ios/chrome/test/earl_grey:test_support",
     "//ios/testing:ios_test_support",
     "//ios/third_party/earl_grey",
     "//ios/web:test_support",
     "//net",
     "//ui/base",
   ]
   libs = [ "XCTest.framework" ]
 }