Move Posix file utils to the base namespace.

base/rand_util_posix.cc

 // 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.
 
 #include "base/rand_util.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <unistd.h>
 
@@ skipping 28 matching lines @@
 
 }  // namespace
 
 namespace base {
 
 // NOTE: This function must be cryptographically secure. http://crbug.com/140076
 uint64 RandUint64() {
   uint64 number;
 
   int urandom_fd = g_urandom_fd.Pointer()->fd();
-  bool success = file_util::ReadFromFD(urandom_fd,
-                                       reinterpret_cast<char*>(&number),
-                                       sizeof(number));
+  bool success = ReadFromFD(urandom_fd, reinterpret_cast<char*>(&number),
+                            sizeof(number));
   CHECK(success);
 
   return number;
 }
 
 int GetUrandomFD(void) {
   return g_urandom_fd.Pointer()->fd();
 }
 
 }  // namespace base