Move remoting::GetUsername() from remoting/base to remoting/host

remoting/host/username.cc

+// Copyright 2013 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 "remoting/host/username.h"
+
+#include <vector>
+
+#include "base/logging.h"
+
+#if defined(OS_POSIX)
+#include <pwd.h>
+#include <sys/types.h>
+#include <unistd.h>
+#endif  // defined(OS_POSIX)
+
+namespace remoting {
+
+std::string GetUsername() {
+#if defined(OS_POSIX)
+  long buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
+  if (buf_size <= 0)
+    return std::string();
+
+  std::vector<char> buf(buf_size);
+  struct passwd passwd;
+  struct passwd* passwd_result = NULL;
+  getpwuid_r(getuid(), &passwd, &(buf[0]), buf_size, &passwd_result);
+  return passwd_result ? passwd_result->pw_name : std::string();
+#else  // !defined(OS_POSIX)
+  NOTIMPLEMENTED();
+  return std::string();
+#endif  // defined(OS_POSIX)
+}
+
+}  // namespace remoting