GN/Win: support win_toolchain asset?

CQ_INCLUDE_TRYBOTS=master.client.skia.compile:Build-Win-MSVC-x86_64-Debug-GN-Trybot

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=3246

Change-Id: Ib38d4f16788bc27ad81975a4c1b0a732e5df1de3
Reviewed-on: https://skia-review.googlesource.com/3246
Reviewed-by: Mike Klein <mtklein@chromium.org>
Commit-Queue: Mike Klein <mtklein@chromium.org>
diff --git a/gn/BUILD.gn b/gn/BUILD.gn
index 7dc8f47..2ced468 100644
--- a/gn/BUILD.gn
+++ b/gn/BUILD.gn
@@ -54,15 +54,24 @@
       "NOMINMAX",
     ]
     include_dirs = [
+      "$windk/VC/include",
+      # For local builds.
       "$windk/../Windows Kits/10/Include/10.0.10150.0/ucrt",
       "$windk/../Windows Kits/8.1/Include/shared",
       "$windk/../Windows Kits/8.1/Include/um",
-      "$windk/VC/include",
+      # For builds using win_toolchain asset.
+      "$windk/win_sdk/Include/10.0.10586.0/shared",
+      "$windk/win_sdk/Include/10.0.10586.0/ucrt",
+      "$windk/win_sdk/Include/10.0.10586.0/um",
     ]
     lib_dirs = [
+      "$windk/VC/lib/amd64",
+      # For local builds.
       "$windk/../Windows Kits/10/Lib/10.0.10150.0/ucrt/x64",
       "$windk/../Windows Kits/8.1/Lib/winv6.3/um/x64",
-      "$windk/VC/lib/amd64",
+      # For builds using win_toolchain asset.
+      "$windk/win_sdk/Lib/10.0.10586.0/ucrt/x64",
+      "$windk/win_sdk/Lib/10.0.10586.0/um/x64",
     ]
   } else {
     cflags += [
@@ -367,8 +376,7 @@
   }
 
   tool("stamp") {
-    win_stamp_path = rebase_path("win_stamp.py")
-    command = "python $win_stamp_path {{output}}"
+    command = "cmd.exe /c echo > {{output}}"
   }
 }
 
diff --git a/gn/win_stamp.py b/gn/win_stamp.py
deleted file mode 100644
index 3d23dd8..0000000
--- a/gn/win_stamp.py
+++ /dev/null
@@ -1,11 +0,0 @@
-#!/usr/bin/env python
-#
-# Copyright 2016 Google Inc.
-#
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-# Implement stamp for windows.
-
-import sys
-open(sys.argv[1], 'w').close()
diff --git a/infra/bots/recipe_modules/flavor/gn_flavor.py b/infra/bots/recipe_modules/flavor/gn_flavor.py
index 5742319..3602737 100644
--- a/infra/bots/recipe_modules/flavor/gn_flavor.py
+++ b/infra/bots/recipe_modules/flavor/gn_flavor.py
@@ -57,7 +57,9 @@
     target_arch   = self.m.vars.builder_cfg.get('target_arch',   '')
 
     clang_linux   = str(self.m.vars.slave_dir.join('clang_linux'))
-    win_toolchain = str(self.m.vars.slave_dir.join('t'))
+    win_toolchain = str(self.m.vars.slave_dir.join(
+      't', 'depot_tools', 'win_toolchain', 'vs_files',
+      '95ddda401ec5678f15eeed01d2bee08fcbc5ee97'))
 
     cc, cxx = None, None
     extra_cflags = []
diff --git a/infra/bots/recipes/swarm_compile.expected/Build-Win-MSVC-x86-Release-GN.json b/infra/bots/recipes/swarm_compile.expected/Build-Win-MSVC-x86-Release-GN.json
index 49a9c7a..f3ccd72 100644
--- a/infra/bots/recipes/swarm_compile.expected/Build-Win-MSVC-x86-Release-GN.json
+++ b/infra/bots/recipes/swarm_compile.expected/Build-Win-MSVC-x86-Release-GN.json
@@ -136,7 +136,7 @@
       "gn.bat",
       "gen",
       "[CUSTOM_C:\\_B_WORK]\\skia\\out\\Build-Win-MSVC-x86-Release-GN\\Release",
-      "--args=is_debug=false target_cpu=\"x86\" windk=\"[SLAVE_BUILD]\\t\""
+      "--args=is_debug=false target_cpu=\"x86\" windk=\"[SLAVE_BUILD]\\t\\depot_tools\\win_toolchain\\vs_files\\95ddda401ec5678f15eeed01d2bee08fcbc5ee97\""
     ],
     "cwd": "[CUSTOM_C:\\_B_WORK]\\skia",
     "env": {