linux: Move linux_util.h from gfx/ to ui/base/gtk.

ui/gfx/linux_util.h

-// 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.
-
-#ifndef UI_GFX_LINUX_UTIL_H_
-#define UI_GFX_LINUX_UTIL_H_
-#pragma once
-
-#include <string>
-
-#include "ui/base/ui_export.h"
-
-namespace gfx {
-
-// Change windows accelerator style to GTK style. (GTK uses _ for
-// accelerators.  Windows uses & with && as an escape for &.)
-UI_EXPORT std::string ConvertAcceleratorsFromWindowsStyle(
-    const std::string& label);
-
-// Removes the "&" accelerators from a Windows label.
-UI_EXPORT std::string RemoveWindowsStyleAccelerators(const std::string& label);
-
-// Escapes "&" characters by doubling them so that later calling
-// ConvertAcceleratorsFromWindowsStyle() will return the original string (except
-// with "_" characters doubled, to escape them for GTK).
-UI_EXPORT std::string EscapeWindowsStyleAccelerators(const std::string& label);
-
-}  // namespace gfx
-
-#endif  // UI_GFX_LINUX_UTIL_H_