Move gtest/gmock BUILD.gn files to main tree.

testing/gtest/BUILD.gn

 # Copyright (c) 2013 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.
 
 config("gtest_config") {
   defines = [
     "UNIT_TEST",
 
     # 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 headers need to be able to find themselves.
   include_dirs = [ "include" ]
 
-  if (is_win) {
-    cflags = [ "/wd4800" ]  # Unused variable warning.
-  }
-
   if (is_posix) {
     defines += [
       # gtest isn't able to figure out when RTTI is disabled for gcc
       # versions older than 4.3.2, and assumes it's enabled.  Our Mac
       # and Linux builds disable RTTI, and cannot guarantee that the
       # compiler will be 4.3.2. or newer.  The Mac, for example, uses
       # 4.2.1 as that is the latest available on that platform.  gtest
       # must be instructed that RTTI is disabled here, and for any
       # direct dependents that might include gtest headers.
       "GTEST_HAS_RTTI=0",
@@ skipping 40 matching lines @@
     sources += [
       "../gtest_mac.h",
       "../gtest_mac.mm",
       "../platform_test_mac.mm",
     ]
   }
 
   include_dirs = [ "." ]
 
   all_dependent_configs = [ ":gtest_config" ]
+  if (is_win) {
+    all_dependent_configs += [
+      "//build/config/win:disable_unused_variable_warning",
+    ]
+  }
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
 }