Move safe_strerror to posix directory and the base namespace

base/posix/safe_strerror.h

 // Copyright (c) 2011 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_SAFE_STRERROR_POSIX_H_
-#define BASE_SAFE_STRERROR_POSIX_H_
+#ifndef BASE_POSIX_SAFE_STRERROR_H_
+#define BASE_POSIX_SAFE_STRERROR_H_
 
 #include <string>
 
 #include "base/base_export.h"
 
+namespace base {
+
 // BEFORE using anything from this file, first look at PLOG and friends in
 // logging.h and use them instead if applicable.
 //
 // This file declares safe, portable alternatives to the POSIX strerror()
 // function. strerror() is inherently unsafe in multi-threaded apps and should
 // never be used. Doing so can cause crashes. Additionally, the thread-safe
 // alternative strerror_r varies in semantics across platforms. Use these
 // functions instead.
 
 // Thread-safe strerror function with dependable semantics that never fails.
 // It will write the string form of error "err" to buffer buf of length len.
 // If there is an error calling the OS's strerror_r() function then a message to
 // that effect will be printed into buf, truncating if necessary. The final
 // result is always null-terminated. The value of errno is never changed.
 //
 // Use this instead of strerror_r().
 BASE_EXPORT void safe_strerror_r(int err, char *buf, size_t len);
 
 // Calls safe_strerror_r with a buffer of suitable size and returns the result
 // in a C++ string.
 //
 // Use this instead of strerror(). Note though that safe_strerror_r will be
 // more robust in the case of heap corruption errors, since it doesn't need to
 // allocate a string.
 BASE_EXPORT std::string safe_strerror(int err);
 
-#endif  // BASE_SAFE_STRERROR_POSIX_H_
+}  // namespace base
+
+#endif  // BASE_POSIX_SAFE_STRERROR_H_