Specify GTEST_LANG_CXX11 to 1 explicitly rather than let gtest detect it

build/secondary/testing/gtest/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_overrides/gtest.gni")
 
 config("gtest_config") {
   visibility = [
     ":*",
     "//testing/gmock:*",  # gmock also shares this config.
   ]
 
   defines = [
     # In order to allow regex matches in gtest to be shared between Windows
     # and other systems, we tell gtest to always use it's internal engine.
     "GTEST_HAS_POSIX_RE=0",
+    "GTEST_LANG_CXX11=1",
   ]
 
   # Gtest headers need to be able to find themselves.
   include_dirs = [ "include" ]
 
   if (is_win) {
     cflags = [ "/wd4800" ]  # Unused variable warning.
   }
 }
 
@@ skipping 93 matching lines @@
 
 source_set("gtest_main") {
   testonly = true
   sources = [
     "src/gtest_main.cc",
   ]
   deps = [
     ":gtest",
   ]
 }