Remove Windows-related GN build configuration

build/config/win/visual_studio_version.gni

-# Copyright 2014 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.
-
-declare_args() {
-  # Path to Visual Studio. If empty, the default is used which is to use the
-  # automatic toolchain in depot_tools. If set, you must also set the
-  # visual_studio_version and wdk_path.
-  visual_studio_path = ""
-
-  # Version of Visual Studio pointed to by the visual_studio_path.
-  # Use "2013" for Visual Studio 2013, or "2013e" for the Express version.
-  visual_studio_version = ""
-
-  # Directory of the Windows driver kit. If visual_studio_path is empty, this
-  # will be auto-filled.
-  wdk_path = ""
-
-  # Full path to the Windows SDK, not including a backslash at the end.
-  # This value is the default location, override if you have a different
-  # installation location.
-  windows_sdk_path = "C:\Program Files (x86)\Windows Kits\8.1"
-}
-
-if (visual_studio_path == "") {
-  toolchain_data =
-      exec_script("../../vs_toolchain.py", [ "get_toolchain_dir" ], "scope")
-  visual_studio_path = toolchain_data.vs_path
-  windows_sdk_path = toolchain_data.sdk_path
-  visual_studio_version = toolchain_data.vs_version
-  wdk_path = toolchain_data.wdk_dir
-  visual_studio_runtime_dirs = toolchain_data.runtime_dirs
-} else {
-  assert(visual_studio_version != "",
-         "You must set the visual_studio_version if you set the path")
-  assert(wdk_path != "",
-         "You must set the wdk_path if you set the visual studio path")
-  visual_studio_runtime_dirs = []
-}