Enable the -Wundef warning for clang

webrtc/modules/desktop_capture/screen_capturer_unittest.cc

 /*
  *  Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include <string.h>
 
 #include <algorithm>
 #include <initializer_list>
 #include <memory>
 #include <utility>
 
 #include "webrtc/modules/desktop_capture/screen_capturer.h"
 
-#include "testing/gmock/include/gmock/gmock.h"
-#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/test/gmock.h"
+#include "webrtc/test/gtest.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/logging.h"
 #include "webrtc/modules/desktop_capture/rgba_color.h"
 #include "webrtc/modules/desktop_capture/desktop_capture_options.h"
 #include "webrtc/modules/desktop_capture/desktop_frame.h"
 #include "webrtc/modules/desktop_capture/desktop_region.h"
 #include "webrtc/modules/desktop_capture/screen_capturer_mock_objects.h"
 #include "webrtc/modules/desktop_capture/screen_drawer.h"
 #include "webrtc/system_wrappers/include/sleep.h"
@@ skipping 368 matching lines @@
        DISABLED_MaybeCaptureUpdatedRegionWithDirectxCapturer) {
   // Even DirectX capturer is not supported in current system, we should be able
   // to select a usable capturer.
   MaybeCreateDirectxCapturer();
   TestCaptureUpdatedRegion();
 }
 
 #endif  // defined(WEBRTC_WIN)
 
 }  // namespace webrtc