Laying the groundwork for targeting WinRT.

build/config/BUILDCONFIG.gn

 # Copyright (c) 2013 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.
 
 if (target_os == "") {
   target_os = host_os
 }
 
 if (target_cpu == "") {
   if (target_os == "android") {
@@ skipping 135 matching lines @@
 # - is_mac is set only for desktop Mac. It is not set on iOS.
 # - is_posix is true for mac and any Unix-like system (basically everything
 #   except Windows).
 # - is_linux is true for desktop Linux and ChromeOS, but not Android (which is
 #   generally too different despite being based on the Linux kernel).
 #
 # Do not add more is_* variants here for random lesser-used Unix systems like
 # aix or one of the BSDs. If you need to check these, just check the
 # current_os value directly.
 
-if (current_os == "win") {
+if (current_os == "win" || current_os == "winrt_81" ||
+    current_os == "winrt_81_phone" || current_os == "winrt_10") {
   is_android = false
   is_chromeos = false
   is_ios = false
   is_linux = false
   is_mac = false
   is_nacl = false
   is_posix = false
   is_win = true
 } else if (current_os == "mac") {
   is_android = false
@@ skipping 199 matching lines @@
 ]
 if (is_win) {
   _native_compiler_configs += [
     "//build/config/win:lean_and_mean",
     "//build/config/win:nominmax",
     "//build/config/win:sdk",
     "//build/config/win:unicode",
     "//build/config/win:winver",
   ]
 }
+if (current_os == "winrt_81" || current_os == "winrt_81_phone" ||
+    current_os == "winrt_10") {
+  _native_compiler_configs += [ "//build/config/win:target_winrt" ]
+}
 if (is_posix) {
   _native_compiler_configs += [
     "//build/config/gcc:no_exceptions",
     "//build/config/gcc:symbol_visibility_hidden",
   ]
 }
 
 if (is_linux) {
   _native_compiler_configs += [ "//build/config/linux:sdk" ]
 } else if (is_mac) {
@@ skipping 136 matching lines @@
 # default toolchain.
 
 if (is_win) {
   # On windows we use the same toolchain for host and target by default.
   # TODO(dpranke): rename the toolchains to x64 and x86 to match current_cpu.
   if (current_cpu == "x64") {
     host_toolchain = "//build/toolchain/win:64"
   } else if (current_cpu == "x86") {
     host_toolchain = "//build/toolchain/win:32"
   }
-  set_default_toolchain("$host_toolchain")
+
+  if (current_os == "win") {
+    set_default_toolchain("$host_toolchain")
+  } else {  # WinRT variants

[brettw, 2015/07/22 20:29:19]

Just eliminate this and make the whole thing one big if/else block.

+    if (current_cpu == "x64") {
+      set_default_toolchain("//build/toolchain/win:winrt_x64")
+    } else if (current_cpu == "x86") {
+      set_default_toolchain("//build/toolchain/win:winrt_x86")
+    }
+  }
 } else if (is_android) {
   if (host_os == "linux") {
     # Use clang for the x86/64 Linux host builds.
     if (host_cpu == "x86" || host_cpu == "x64") {
       host_toolchain = "//build/toolchain/linux:clang_$host_cpu"
     } else {
       host_toolchain = "//build/toolchain/linux:$host_cpu"
     }
   } else if (host_os == "mac") {
     host_toolchain = "//build/toolchain/mac:clang_$host_cpu"
@@ skipping 226 matching lines @@
       }
       if (defined(invoker.testonly)) {
         testonly = invoker.testonly
       }
       if (defined(invoker.visibility)) {
         visibility = invoker.visibility
       }
     }
   }
 }