Beginning work on GN build

build/config/nacl/config.gni

+# Copyright 2015 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.
+
+import("//build/config/features.gni")
+
+declare_args() {
+  # Native Client supports both Newlib and Glibc C libraries where Newlib
+  # is assumed to be the default one; use this to determine whether Glibc
+  # is being used instead.
+  is_nacl_glibc = false
+}
+
+is_nacl_irt = false
+is_nacl_nonsfi = false
+
+if (enable_nacl) {
+  nacl_toolchain_dir = "//native_client/toolchain/${host_os}_x86"
+
+  if (is_nacl_glibc) {
+    if (current_cpu == "x86" || current_cpu == "x64") {
+      nacl_toolchain_package = "nacl_x86_glibc"
+    } else if (current_cpu == "arm") {
+      nacl_toolchain_package = "nacl_arm_glibc"
+    }
+  } else {
+    nacl_toolchain_package = "pnacl_newlib"
+  }
+
+  if (current_cpu == "pnacl") {
+    _nacl_tuple = "pnacl"
+  } else if (current_cpu == "x86" || current_cpu == "x64") {
+    _nacl_tuple = "x86_64-nacl"
+  } else if (current_cpu == "arm") {
+    _nacl_tuple = "arm-nacl"
+  } else if (current_cpu == "mipsel") {
+    _nacl_tuple = "mipsel-nacl"
+  }
+
+  nacl_toolchain_bindir = "${nacl_toolchain_dir}/${nacl_toolchain_package}/bin"
+  nacl_toolchain_tooldir =
+      "${nacl_toolchain_dir}/${nacl_toolchain_package}/${_nacl_tuple}"
+  nacl_toolprefix = "${nacl_toolchain_bindir}/${_nacl_tuple}-"
+
+  nacl_irt_toolchain = "//build/toolchain/nacl:irt_" + target_cpu
+  is_nacl_irt = current_toolchain == nacl_irt_toolchain
+
+  # Non-SFI mode is a lightweight sandbox used by Chrome OS for running ARC
+  # applications.
+  nacl_nonsfi_toolchain = "//build/toolchain/nacl:newlib_pnacl_nonsfi"
+  is_nacl_nonsfi = current_toolchain == nacl_nonsfi_toolchain
+}