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

base/nix/mime_util_xdg.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_NIX_MIME_UTIL_XDG_H_
 #define BASE_NIX_MIME_UTIL_XDG_H_
-#pragma once
 
 #include <string>
 
 #include "base/base_export.h"
 #include "build/build_config.h"
 
 class FilePath;
 
 namespace base {
 namespace nix {
@@ skipping 17 matching lines @@
 // Gets the file name for an icon given the mime type and icon pixel size.
 // Where an icon is a square image of |size| x |size|.
 // This will try to find the closest matching icon. If that's not available,
 // then a generic icon, and finally an empty FilePath if all else fails.
 BASE_EXPORT FilePath GetMimeIcon(const std::string& mime_type, size_t size);
 
 }  // namespace nix
 }  // namespace base
 
 #endif  // BASE_NIX_MIME_UTIL_XDG_H_