[GN] Fix generate Xcode project for macOS to work with Xcode 8.

tools/gn/xcode_writer.cc

 // Copyright 2016 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.
 
 #include "tools/gn/xcode_writer.h"
 
 #include <iomanip>
 #include <map>
 #include <memory>
 #include <sstream>
@@ skipping 24 matching lines @@
   const Value* target_os_value = args.GetArgOverride(variables::kTargetOs);
   if (target_os_value) {
     if (target_os_value->type() == Value::STRING) {
       if (target_os_value->string_value() == "ios")
         return XcodeWriter::WRITER_TARGET_OS_IOS;
     }
   }
   return XcodeWriter::WRITER_TARGET_OS_MACOS;
 }
 
-std::string GetArchs(const Args& args) {
-  const Value* target_cpu_value = args.GetArgOverride(variables::kTargetCpu);
-  if (target_cpu_value) {
-    if (target_cpu_value->type() == Value::STRING) {
-      if (target_cpu_value->string_value() == "x86")
-        return "i386";
-      if (target_cpu_value->string_value() == "x64")
-        return "x86_64";
-      if (target_cpu_value->string_value() == "arm")
-        return "armv7";
-      if (target_cpu_value->string_value() == "armv7")
-        return "armv7";
-      if (target_cpu_value->string_value() == "arm64")
-        return "armv64";
-    }
-  }
-  return "x86_64";
-}
-
 std::string GetBuildScript(const std::string& target_name,
                            const std::string& build_path,
                            const std::string& ninja_extra_args) {
   std::stringstream script;
   script << "echo note: \"Compile and copy " << target_name << " via ninja\"\n"
          << "exec ";
   if (!build_path.empty())
     script << "env PATH=\"" << build_path << "\" ";
   script << "ninja -C .";
   if (!ninja_extra_args.empty())
@@ skipping 76 matching lines @@
   const XcodeWriter::TargetOsType target_os =
       GetTargetOs(build_settings->build_args());
 
   PBXAttributes attributes;
   switch (target_os) {
     case XcodeWriter::WRITER_TARGET_OS_IOS:
       attributes["SDKROOT"] = "iphoneos";
       attributes["TARGETED_DEVICE_FAMILY"] = "1,2";
       break;
     case XcodeWriter::WRITER_TARGET_OS_MACOS:
-      attributes["ARCHS"] = GetArchs(build_settings->build_args());
-      attributes["SDKROOT"] = "macosx10.11";
+      attributes["SDKROOT"] = "macosx";
       break;
   }
 
   const std::string source_path =
       base::FilePath::FromUTF8Unsafe(
           RebasePath("//", build_settings->build_dir()))
           .StripTrailingSeparators()
           .AsUTF8Unsafe();
 
   std::string config_name = build_settings->build_dir()
@@ skipping 249 matching lines @@
     for (auto* object : pair.second) {
       object->Print(out, 2);
     }
     out << "/* End " << ToString(pair.first) << " section */\n";
   }
 
   out << "\t};\n"
       << "\trootObject = " << project->Reference() << ";\n"
       << "}\n";
 }