Linux: Move base/mime_util* to base/nix. It's not used on any other platform.

base/mime_util.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_MIME_UTIL_H_
-#define BASE_MIME_UTIL_H_
-#pragma once
-
-#include <string>
-
-#include "base/base_export.h"
-#include "build/build_config.h"
-
-class FilePath;
-
-namespace mime_util {
-
-// Gets the mime type for a file based on its filename. The file path does not
-// have to exist. Please note because it doesn't touch the disk, this does not
-// work for directories.
-// If the mime type is unknown, this will return application/octet-stream.
-BASE_EXPORT std::string GetFileMimeType(const FilePath& filepath);
-
-// Get the mime type for a byte vector.
-BASE_EXPORT std::string GetDataMimeType(const std::string& data);
-
-#if defined(TOOLKIT_USES_GTK)
-// This detects the current GTK theme by calling gtk_settings_get_default().
-// It should only be executed on the UI thread and must be called before
-// GetMimeIcon().
-BASE_EXPORT void DetectGtkTheme();
-#endif
-
-// 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 mime_util
-
-#endif  // BASE_MIME_UTIL_H_