Add initial BUILD.gn in platform/wtf/, and move first a few files there.

third_party/WebKit/Source/wtf/CryptographicallyRandomNumber.cpp

-/*
- * Copyright (c) 1996, David Mazieres <dm@uun.org>
- * Copyright (c) 2008, Damien Miller <djm@openbsd.org>
- *
- * Permission to use, copy, modify, and distribute this software for any
- * purpose with or without fee is hereby granted, provided that the above
- * copyright notice and this permission notice appear in all copies.
- *
- * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
- * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
- * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
- * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
- * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
- * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
- */
-
-#include "wtf/CryptographicallyRandomNumber.h"
-
-#include "base/rand_util.h"
-#include <string.h>
-
-namespace WTF {
-
-static bool s_shouldUseAlwaysZeroRandomSourceForTesting = false;
-
-void setAlwaysZeroRandomSourceForTesting() {
-  s_shouldUseAlwaysZeroRandomSourceForTesting = true;
-}
-
-uint32_t cryptographicallyRandomNumber() {
-  uint32_t result;
-  cryptographicallyRandomValues(&result, sizeof(result));
-  return result;
-}
-
-void cryptographicallyRandomValues(void* buffer, size_t length) {
-  if (s_shouldUseAlwaysZeroRandomSourceForTesting) {
-    memset(buffer, '\0', length);
-    return;
-  }
-
-  // This should really be crypto::RandBytes(), but WTF can't depend on crypto.
-  // The implementation of crypto::RandBytes() is just calling
-  // base::RandBytes(), so both are actually same.
-  base::RandBytes(buffer, length);
-}
-
-}  // namespace WTF