GN threading refactor

tools/gn/gyp_target_writer.cc

Index: tools/gn/gyp_target_writer.cc
diff --git a/tools/gn/gyp_target_writer.cc b/tools/gn/gyp_target_writer.cc
index 8a55bdc3dd28c55ea0ee577a8799eccfd4517fba..29cec2c47b0e144715ee125c89a61469b1031d3d 100644
--- a/tools/gn/gyp_target_writer.cc
+++ b/tools/gn/gyp_target_writer.cc
@@ -9,6 +9,7 @@
 #include "base/file_util.h"
 #include "base/files/file_path.h"
 #include "tools/gn/build_settings.h"
+#include "tools/gn/builder_record.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/gyp_binary_target_writer.h"
 #include "tools/gn/scheduler.h"
@@ -30,15 +31,16 @@ void GypTargetWriter::WriteFile(const SourceFile& gyp_file,
                                 Err* err) {
   if (targets.empty())
     return;
-  const BuildSettings* debug_build_settings =
-      targets[0].debug->settings()->build_settings();
+  const Settings* debug_settings =
+      targets[0].debug->item()->AsTarget()->settings();
+  const BuildSettings* debug_build_settings = debug_settings->build_settings();
 
   std::stringstream file;
   file << "# Generated by GN. Do not edit.\n\n";
   file << "{\n";
   file << "  'skip_includes': 1,\n";
 
-  if (targets[0].debug->settings()->IsMac()) {
+  if (debug_settings->IsMac()) {
     // Global settings for make/ninja. This must match common.gypi :(
     file << "  'make_global_settings': [\n";
     file << "    ['CC', 'third_party/llvm-build/Release+Asserts/bin/clang'],\n";
@@ -53,7 +55,8 @@ void GypTargetWriter::WriteFile(const SourceFile& gyp_file,
   file << "  'targets': [\n";
 
   for (size_t i = 0; i < targets.size(); i++) {
-    switch (targets[i].debug->output_type()) {
+    const Target* cur = targets[i].debug->item()->AsTarget();
+    switch (cur->output_type()) {
       case Target::COPY_FILES:
       case Target::CUSTOM:
       case Target::GROUP: