Add namespace and re-arrange PDFium's local copy of chromium /base.

third_party/macros.h

-// 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.
-
-// This file contains macros and macro-like constructs (e.g., templates) that
-// are commonly used throughout Chromium source. (It may also contain things
-// that are closely related to things that are commonly used that belong in this
-// file.)
-
-#ifndef BASE_MACROS_H_
-#define BASE_MACROS_H_
-
-// The COMPILE_ASSERT macro can be used to verify that a compile time
-// expression is true. For example, you could use it to verify the
-// size of a static array:
-//
-//   COMPILE_ASSERT(ARRAYSIZE_UNSAFE(content_type_names) == CONTENT_NUM_TYPES,
-//                  content_type_names_incorrect_size);
-//
-// or to make sure a struct is smaller than a certain size:
-//
-//   COMPILE_ASSERT(sizeof(foo) < 128, foo_too_large);
-//
-// The second argument to the macro is the name of the variable. If
-// the expression is false, most compilers will issue a warning/error
-// containing the name of the variable.
-
-#undef COMPILE_ASSERT
-#define COMPILE_ASSERT(expr, msg) static_assert(expr, #msg)
-
-#endif  // BASE_MACROS_H_