Remove #pragma once. Just from base/ for now.

base/gtest_prod_util.h

 // Copyright (c) 2012 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.
 
 #ifndef BASE_GTEST_PROD_UTIL_H_
 #define BASE_GTEST_PROD_UTIL_H_
-#pragma once
 
 #include "testing/gtest/include/gtest/gtest_prod.h"
 
 // This is a wrapper for gtest's FRIEND_TEST macro that friends
 // test with all possible prefixes. This is very helpful when changing the test
 // prefix, because the friend declarations don't need to be updated.
 //
 // Example usage:
 //
 // class MyClass {
@@ skipping 42 matching lines @@
 //   foo_class.private_var = true;
 // }
 
 #define FORWARD_DECLARE_TEST(test_case_name, test_name) \
   class test_case_name##_##test_name##_Test; \
   class test_case_name##_##DISABLED_##test_name##_Test; \
   class test_case_name##_##FLAKY_##test_name##_Test; \
   class test_case_name##_##FAILS_##test_name##_Test
 
 #endif  // BASE_GTEST_PROD_UTIL_H_