Remove arraysize.h gcc hack and Chromium override.

webrtc/overrides/webrtc/base/arraysize.h

Index: webrtc/overrides/webrtc/base/arraysize.h
diff --git a/webrtc/overrides/webrtc/base/arraysize.h b/webrtc/overrides/webrtc/base/arraysize.h
deleted file mode 100644
index abc1240fe56161ac2d1263106602a50e48854885..0000000000000000000000000000000000000000
--- a/webrtc/overrides/webrtc/base/arraysize.h
+++ /dev/null
@@ -1,20 +0,0 @@
-/*
- *  Copyright 2015 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.
- */
-
-// This file overrides the inclusion of webrtc/base/arraysize.h
-// We do this because in Chromium it redefines arraysize, which is already
-// defined in base/macros.h.
-
-#ifndef OVERRIDES_WEBRTC_BASE_ARRAYSIZE_H__
-#define OVERRIDES_WEBRTC_BASE_ARRAYSIZE_H__
-
-#include "base/macros.h"
-
-#endif  // OVERRIDES_WEBRTC_BASE_ARRAYSIZE_H__