Limiting SwiftShader compilation to x64 and x86 architectures

BUILD.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.
 
 # This is the root build file for GN. GN will start processing by loading this
 # file, and recursively load all dependencies until all dependencies are either
 # resolved or known not to exist (which will cause the build to fail). So if
 # you add a new build file, there must be some path of dependencies from this
 # file to your new one or GN won't know about it.
 
@@ skipping 509 matching lines @@
   }
 
   if (is_ios || is_win || (is_linux && !is_chromeos)) {
     deps += [
       "//base:base_i18n_perftests",
       "//base:base_perftests",
       "//google_apis:google_apis_unittests",
     ]
   }
 
-  if (is_win || is_mac || is_linux) {
+  if ((is_win || is_mac || is_linux) &&
+      (target_cpu == "x86" || target_cpu == "x64")) {
     deps += [ "//third_party/swiftshader" ]
   }
 
   # TODO(GYP): Figure out which of these should (and can) build
   # for chromeos/ios.
   if (!is_chromeos && !is_ios) {
     deps += [
       "//base:build_utf8_validator_tables",
       "//base:check_example",
       "//cc:cc_perftests",
@@ skipping 551 matching lines @@
   assert(target_name != "")  # Mark as used.
   sources = invoker.actual_sources
   assert(
       sources == invoker.actual_sources,
       "Do not use a platform name in your output directory (found \"$root_build_dir\"). http://crbug.com/548283")
 }
 
 assert_valid_out_dir("_unused") {
   actual_sources = [ "$root_build_dir/foo" ]
 }