[infra] Assembles the SDK using GN rather than create_sdk.py

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.
 
 # =============================================================================
 # PLATFORM SELECTION
 # =============================================================================
 #
 # There are two main things to set: "os" and "cpu". The "toolchain" is the name
 # of the GN thing that encodes combinations of these things.
@@ skipping 135 matching lines @@
 # - 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") {
   is_android = false
   is_chromeos = false
+  is_fuchsia = false
+  is_fuchsia_host = 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
   is_chromeos = false
+  is_fuchsia = false
+  is_fuchsia_host = false
   is_ios = false
   is_linux = false
   is_mac = true
   is_nacl = false
   is_posix = true
   is_win = false
 } else if (current_os == "android") {
   is_android = true
   is_chromeos = false
+  is_fuchsia = false
+  is_fuchsia_host = false
   is_ios = false
   is_linux = false
   is_mac = false
   is_nacl = false
   is_posix = true
   is_win = false
 } else if (current_os == "linux") {
   is_android = false
   is_chromeos = false
+  is_fuchsia = false
+  is_fuchsia_host = false
   is_ios = false
   is_linux = true
   is_mac = false
   is_nacl = false
   is_posix = true
   is_win = false
 }
 
 # =============================================================================
 # BUILD OPTIONS
@@ skipping 27 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 (is_posix) {
-  _native_compiler_configs += [
-    "//build/config/gcc:no_exceptions",
-  ]
+  _native_compiler_configs += [ "//build/config/gcc:no_exceptions" ]
 }
 
 if (is_linux) {
   _native_compiler_configs += [ "//build/config/linux:sdk" ]
 } else if (is_mac) {
   _native_compiler_configs += [ "//build/config/mac:sdk" ]
 } else if (is_android) {
   _native_compiler_configs += [ "//build/config/android:sdk" ]
 }
 
@@ skipping 214 matching lines @@
       sources = invoker.sources
     }
     if (defined(invoker.testonly)) {
       testonly = invoker.testonly
     }
     if (defined(invoker.visibility)) {
       visibility = invoker.visibility
     }
   }
 }